System for supplying gas to floating structures

Abstract

The present invention relates to a supply system (1) for supplying gas to a high-pressure gas consumption device (4) and a low-pressure gas consumption device (5) of a floating structure, comprising a first supply circuit (2), a high-pressure evaporator (11), a second supply circuit (3), and a gas return line (14); wherein the supply system (1) comprises a first heat exchanger (6) and a second heat exchanger (7), and the first supply circuit (2) comprises a second pumping device (10) inserted between the first heat exchanger (6) and the second heat exchanger (7), and the supply system (1) comprises a recirculation branch (15), and the first supply circuit (2) comprises a first bypass branch (16) and a second bypass branch (17).

Description

Technology Field

[0001] The present invention relates to the field of floating structures for transporting and / or storing gas in a liquid state, and more specifically to a gas supply system for supplying gas to a consuming device included within such floating structures and a method for managing such a system. Background Technology

[0002] While a floating structure is in motion containing a tank of liquid gas configured to be consumed and / or delivered to a destination, the floating structure may use at least a portion of the liquid gas to supply at least one of its engines through a gas supply system. This applies to a vessel equipped with a high-pressure propulsion engine of the ME-GI type. To supply this type of engine, the gas must be compressed to ultra-high pressure by a special compressor capable of compressing the gas to an absolute pressure of 300 bar, but such a compressor is expensive, incurs high maintenance costs, and causes vibration within the vessel.

[0003] An alternative to installing such a high-pressure compressor is to vaporize the gas into a liquid state at an absolute pressure of 300 bar using a high-pressure pumping device before the gas is sent to the propulsion engine. Since this solution does not remove the gas in a vapor state (or BOG, meaning "Boil-Off Gas") that naturally forms within the tank containing at least part of the cargo, a low-pressure compressor is installed to supply the gas in vapor form to an auxiliary engine that can consume the gas at low pressure.

[0004] In addition, it is known that downstream of the compression device, excess gas in the form of steam is recirculated and reliquefied by one or more heat exchanges operated by one or more heat exchangers between a gas in a liquid state configured to be supplied to a high-pressure propulsion engine and a gas in a steam state configured to be reliquefied.

[0005] When the compressor used is an oil compressor, disadvantages may arise within the supply system, which applies to the majority of such system configurations. Although the oil compressor is equipped with filtering means to prevent oil from leaving the compressor and circulating within the supply system, a small amount of oil always escapes the compressor and circulates through the branches of the supply system's circuit.

[0006] If the oil is subsequently circulated through the aforementioned heat exchanger or exchanger, the oil may cool and solidify within the heat exchanger. Over time, the solidified oil accumulates within at least one heat exchanger, clogging it and severely impairing its heat processing capacity. While it is possible to replace the compressor with an oil-free compressor, such replacement is limited and costly.

[0007] The present invention addresses this problem and, accordingly, proposes a supply system for supplying gas to at least one high-pressure gas consuming device and at least one low-pressure gas consuming device of a floating structure comprising at least one tank configured to receive gas, said supply system:

[0008] · At least one first supply circuit comprising at least one first pumping device configured to supply gas to the high-pressure gas consuming device and configured to pump gas taken from the tank in a liquid state,

[0009] · At least one high-pressure evaporator configured to evaporate the gas circulating in the first supply circuit above,

[0010] · At least one second supply circuit comprising at least one compressor configured to supply gas to the low-pressure gas consuming device and configured to compress gas taken from the tank in a vapor state to a pressure compatible with the requirements of the low-pressure gas consuming device,

[0011] · A supply system comprising: at least one gas return line connected to the second supply circuit downstream of the compression device and extending to the tank; wherein the supply system comprises at least one first heat exchanger and at least one second heat exchanger, each configured to operate heat exchange between a gas in a vapor state circulating in the return line and a gas in a liquid state circulating in the first supply circuit, and wherein the first supply circuit comprises a second pumping device inserted between the first heat exchanger and the second heat exchanger.

[0012] The supply system comprises a recirculation branch connected at an inlet to a branch point disposed on the return line between the first heat exchanger and the tank, wherein the recirculation branch comprises an outlet connected to the second supply circuit between the tank and the compression device, and wherein the first supply circuit comprises a first bypass branch disposed in parallel with a first segment of the first supply circuit passing through the first heat exchanger, and a second bypass branch disposed in parallel with a second segment of the first supply circuit passing through the second heat exchanger.

[0013] In addition to being able to supply excess gas in a vapor state to a gas-consuming device while re-liquefying it, the supply system can implement a configuration that ensures the removal of oil accumulated in one or more heat exchangers.

[0014] To this end, the recirculation branch forms a loop of gas in a vapor state between the second supply circuit and the return line, allowing the gas in a vapor state to circulate in the loop within the heat exchanger. This loop may be semi-closed or fully closed according to an embodiment of the supply system according to the present invention. In the case of a semi-closed loop, in addition to ensuring loop-type circulation of gas in a vapor state within the heat exchanger, the gas in a vapor state contained in the tank is always drawn in by a compressor, circulated in the second supply circuit, and always supplied to a low-pressure gas consumption device. This configuration corresponds to a first embodiment of the supply system according to the present invention. The circulation of gas in a vapor state within the heat exchanger causes an increase in internal temperature and the melting of oil accumulated therein, which can then be transported and discharged by the flow of gas in a vapor state. The oil is then circulated to a compressor, where it is filtered and stored.

[0015] To ensure the temperature rise of the heat exchanger, only gas in a vapor state must circulate within it, because the gas in a liquid state circulating in the first supply circuit is at a temperature too low to ensure such a temperature rise. However, supply to the high-pressure gas consuming device must be ensured, including during the operation of melting the oil contained in the heat exchanger. The bypass branch ensures that the gas is supplied to the high-pressure consuming device without the gas in a liquid state hindering the temperature rise of the heat exchanger. Therefore, the gas in a liquid state is initially processed only by the second pumping device, and only the high-pressure evaporator evaporates the gas in a liquid state to ensure that the gas is compatible with the requirements of the high-pressure gas consuming device.

[0016] As described above, the first gas supply circuit is used to meet the fuel requirements of a high-pressure gas consuming device. The high-pressure gas consuming device may be a means of propulsion for a floating structure, for example, an ME-GI engine. The first supply circuit extends from the tank to the high-pressure gas consuming device. The first pumping device is installed at the bottom of the tank and can pump gas in a liquid state to circulate it in the first supply circuit.

[0017] The second pumping device increases the pressure of the liquid gas circulating in the first supply circuit to have a pressure compatible with the supply section of the high-pressure gas consumption device. Positioning the second pumping device between two heat exchangers is particularly advantageous as it ensures efficient heat treatment of the vapor gas circulating in the return line by the liquid gas circulating in the first supply circuit, while avoiding the premature evaporation of the liquid gas that could damage the second pumping device. However, when the liquid gas bypasses the heat exchanger, it continues to be pumped by the second pumping device.

[0018] Since the gas must be in a vapor state before being supplied to a high-pressure gas consuming device, a high-pressure evaporator ensures that the gas evaporates before being supplied to the high-pressure gas consuming device. The high-pressure evaporator is the site of heat exchange between the gas in a liquid state circulating in the first supply circuit and a heat transfer fluid, which is, for example, glycol water, seawater, or steam. The heat transfer fluid must be at a sufficiently high temperature to cause a change of state in the gas, and as a result, the gas enters a steam or supercritical state to be supplied to the high-pressure gas consuming device, regardless of whether the gas in a liquid state has previously passed through a heat exchanger.

[0019] In a configuration for the re-liquefaction of excess gas in a vapor state, before the liquid gas circulating in the first supply circuit is vaporized through a high-pressure evaporator, the liquid gas passes through a first heat exchanger and then through a second heat exchanger. To this end, the first heat exchanger and the second heat exchanger are connected to each other by a section of the first supply circuit so that the liquid gas can pass through the two heat exchangers in succession, said section advantageously includes a second pumping device. Thus, the temperature of the gas in the liquid state tends to rise before passing through the high-pressure evaporator. In this way, the gas circulating in the first supply circuit may be in a two-phase state at the outlet of the second heat exchanger.

[0020] Generally, the gas contained in the tank can be converted into a vapor state naturally or forcibly by a floating structure. All gas within the tank that turns into vapor must be vented to prevent the generation of excess pressure within the tank.

[0021] This function is performed by a second gas supply circuit of the low-pressure gas consuming device. This second supply circuit extends from the tank to the low-pressure gas consuming device. The low-pressure gas consuming device may be an auxiliary engine, such as an electric generator. A compressor on the second supply circuit is responsible for drawing gas from the head of the tank to supply it to the low-pressure gas consuming device and to regulate the pressure within the tank. This compressor may be an oil compressor.

[0022] At the outlet of the compressor, the gas in a vapor state can be supplied to a low-pressure gas consuming device, or it can be circulated through a return line if the low-pressure gas consuming device does not require fuel supply or if the amount of gas in a vapor state is greater than the supply requirements of the low-pressure gas consuming device. Since the return line is connected downstream of the compressor, the gas inhaled by the compressor can be circulated through it, and if the compressor is oil-operated, trace amounts of oil leaked from the compressor can also be circulated.

[0023] The gas in a vapor state circulating in the return line first passes through a second heat exchanger and then through a first heat exchanger before reaching the first supply circuit. As a result of the exchange of heat between the gas in a liquid state circulating in the first supply circuit and the gas in a vapor state circulating in the return line, the temperature of the gas in a vapor state decreases as it passes through the heat exchangers, so that the gas is substantially re-liquefied at the outlet of the first heat exchanger and returns to a liquid state, and can then be circulated to the tank. A small amount of oil accompanying the gas in a vapor state also passes through the heat exchangers and is cooled and solidified within one or the other of the heat exchangers. Although the amount of oil leaking from the compressor is minimal, the accumulation of solidified oil over time eventually hinders the smooth operation of the supply system.

[0024] As mentioned above, the recirculation branch forms a loop that allows the gas to circulate from the return line to the second supply circuit. This allows the gas in a vapor state to circulate multiple times within the heat exchanger, whereas the circulation of the gas in a liquid state is discontinued within these same heat exchangers. Since the gas in a vapor state is at a higher temperature, it causes a temperature rise within the heat exchanger, melting and discharging the oil condensates accumulated therein. Once the oil is completely discharged from the heat exchanger, the configuration of the supply system can be changed again so that the excess gas in a vapor state can be re-liquefied.

[0025] According to a feature of the present invention, the supply system includes a recirculation valve disposed on a recirculation branch and a return valve disposed on a return line between the branch point and the tank. The valve can be switched between an open position and a closed position to allow or prohibit gas circulation in the said branch or circuit, respectively.

[0026] The return valve controls the return of gas to the tank after re-liquefaction. The recirculation valve controls the circulation of the gas in a vapor state so that it circulates in a loop through the heat exchangers to raise the temperature of the heat exchangers. Therefore, if either the recirculation valve or the return valve is opened, the other valve must be closed.

[0027] In the case of loop circulation within the heat exchanger according to the semi-closed loop, that is, according to the first embodiment, the recirculation valve also ensures the expansion of the gas in a vapor state that was previously compressed by the compression device.

[0028] This expansion ensures that the pressure between the vaporized gas coming from the return line and the vaporized gas coming directly from the tank is balanced.

[0029] According to a feature of the present invention, the supply system includes a bypass valve disposed on a first bypass branch and a control valve disposed on a first segment of the first supply circuit. The control valve and the bypass valve cause the temperature of the liquid gas circulating in the first supply circuit to rise so that it passes through the first exchanger or bypasses the first exchanger to melt the oil accumulated therein. As with the valves described above, the control valve and the bypass valve can be switched between an open position and a closed position to allow or prohibit the circulation of gas in the branch or circuit, respectively.

[0030] According to a feature of the present invention, a control valve is positioned in a first segment upstream of a first heat exchanger, and a supply system includes a control valve positioned in a first segment downstream of the first heat exchanger. Advantageously, the first heat exchanger can be completely isolated from the circulation of a liquid gas within the first supply circuit. This prevents a trace amount of the liquid gas from circulating within the first heat exchanger, thereby hindering its temperature rise and / or evaporating therefrom to produce an undesirable pressure rise. Advantageously, the control valve and the control valve are opened or closed simultaneously.

[0031] According to one feature of the present invention, the supply system includes a bypass member disposed on a second bypass branch and a control member disposed on a second segment of the first supply circuit.

[0032] According to another feature of the present invention, a control member is disposed on a second segment upstream of a second heat exchanger, and a supply system includes a control member disposed on a second segment downstream of the second heat exchanger.

[0033] The bypass member, control member, and regulating member are corresponding parts of the valves of the same names described above, but are applied to the second heat exchanger instead of the first heat exchanger. Accordingly, the operation of the bypass member, control member, and regulating member is the same as the operation of the bypass valve, control valve, and regulating valve.

[0034] According to one feature of the present invention, the supply system comprises a first measuring member and a second measuring member configured to measure the pressure of a gas circulating in a return line at the inlet and outlet of a first heat exchanger and / or at the inlet and outlet of a second heat exchanger, respectively. The measuring members are used to detect whether it is time to operate the supply system to remove oil aggregates that may have accumulated in one or both of the heat exchangers.

[0035] This need can be detected by measuring the pressure drop of the gas in a vapor state at the outlet of at least one of the heat exchangers compared to before it enters the same heat exchangers. The pressure drop is represented by the pressure difference between the gas entering and exiting at least one of the heat exchangers. If the pressure difference is high, for example, exceeding 40 mbar for the first heat exchanger or 200 mbar for the second heat exchanger, it means that a significant amount of oil condensate is present and is interfering with the accurate operation of the supply system. This pressure difference can be measured simultaneously at the levels of one or both heat exchangers.

[0036] It may also be advantageous to calculate the change in pressure difference over time to determine when it is meaningful to perform the discharge of oil accumulated in at least one of the heat exchangers. As an example, a fluctuation in pressure difference exceeding 150%, preferably exceeding 100%, in relation to the pressure difference when there is no oil condensation in the heat exchanger is considered to be the moment when the accumulated oil should be discharged.

[0037] According to a feature of the present invention, the supply system includes a first measuring device and a second measuring device configured to measure, respectively, the temperature of a gas circulating in a first supply circuit at the inlet of a first heat exchanger and the temperature of a gas circulating in a return line at the outlet of the first heat exchanger and / or the temperature of a gas circulating in a first supply circuit at the inlet of a second heat exchanger and the temperature of a gas circulating in a return line at the outlet of the second heat exchanger.

[0038] In addition to measuring the pressure of the measuring member, or as an alternative, the need to remove oil aggregates present in either one and / or the other may be detected by the temperature difference between the temperature of the liquid gas circulating in the first supply circuit at the inlet of one of the heat exchangers and the temperature of the gas circulating in the return line at the outlet of the same heat exchanger. Thus, the temperature difference is calculated from the measurement performed in a single heat exchanger. If the difference between these two temperatures is too large, it means that heat exchange in the heat exchanger is not sufficiently efficient because too much oil aggregate is present in the heat exchanger. The temperature difference considered to require oil discharge may be about 10°C, preferably 5°C.

[0039] It may also be advantageous to calculate the change in temperature difference over time to determine at what point it is reasonable to implement the discharge of oil accumulated in at least one of the heat exchangers.

[0040] The measurement of the pressure and temperature differences described above can be implemented simultaneously to double-check the need to remove oil aggregates within one and / or another heat exchanger. During this operation, the pressure difference can be controlled over time to verify that the removal of oil aggregates is proceeding correctly and when this operation can be stopped.

[0041] According to a feature of the present invention, the supply system includes an auxiliary supply branch connected at an inlet to a second supply circuit between a tank and an outlet of a recirculation branch, the auxiliary supply branch includes an outlet connected to a second supply circuit between a connection to a return line and a low-pressure gas consumption device, and the auxiliary supply branch includes a compression member. This configuration constitutes a second embodiment of the present invention.

[0042] In this second embodiment, the gas in a vapor state circulates through a heat exchanger in a completely closed loop. The gas in a vapor state is discharged from the tank and supplied to a low-pressure gas consuming device through an auxiliary supply branch, while the heat exchanger is understood to increase in temperature over time due to a defined constant amount of gas in a vapor state circulating in the loop between the second supply circuit and the return line.

[0043] According to a feature of the present invention, the second supply circuit includes a first auxiliary valve disposed between the inlet of the auxiliary supply branch and the outlet of the recirculation branch, and a second auxiliary valve disposed between the connection to the return line and the outlet of the auxiliary supply branch. According to a second embodiment of the supply system according to the present invention, the first auxiliary valve and the second auxiliary valve allow complete isolation of the gas loop in the steam state, thereby ensuring a temperature rise of the heat exchanger. This means that the tank and the low-pressure gas consuming device communicate with each other only through the auxiliary supply branch. Accordingly, the auxiliary valve is in a closed position when it is necessary to discharge oil accumulated in at least one of the heat exchangers.

[0044] According to the features of the present invention, a first pumping device is configured to increase the pressure of a gas in a liquid state to a value between 6 bar and 17 bar, and a second pumping device is configured to increase the pressure of a gas in a liquid state to a value between 30 bar and 400 bar. The increase in gas pressure by the second pumping device depends on the type of gas being transported and / or stored. The pressure of the gas in a liquid state is increased to a value between 30 bar and 400 bar absolute pressure for use with ammonia or hydrogen, between 30 bar and 70 bar absolute pressure for use with liquefied petroleum gas, and preferably between 150 bar and 400 bar absolute pressure for use with ethane, ethylene, or liquefied natural gas composed mainly of methane.

[0045] According to one feature of the present invention, the compression device is configured to increase the pressure of the gas to a value between 6 bar and 20 bar.

[0046] The present invention also covers a floating structure for storing and / or transporting a gas in a liquid state, said floating structure comprising at least one tank for the gas in a liquid state, at least one high-pressure gas consuming device, at least one low-pressure gas consuming device, and at least one system for supplying gas to these devices as described above.

[0047] The present invention also covers a gas management method used within a floating structure comprising at least one tank configured to receive gas, which is implemented by the supply system described above, and during said method:

[0048] · In the first configuration, the gas is circulated in a liquid state in the first supply circuit within the first heat exchanger and the second heat exchanger, and the gas in a vapor state is circulated to the tank in the return line, and

[0049] · According to the second configuration, the gas in a liquid state is circulated in the first supply circuit within the first bypass branch and the second bypass branch, and the gas in a vapor state is circulated within the recirculation branch.

[0050] From the above, it can be seen that the first configuration corresponds to a configuration in which excess gas in a vapor state is re-liquefied before returning to the tank in assistance to the gas in a liquid state circulating in the first supply circuit and heat exchanger, whereas the second configuration corresponds to a configuration in which gas in a vapor state circulates in a loop within the heat exchanger to generate a temperature rise that ensures the removal of oil aggregates accumulated within the heat exchanger. The supply system can switch from the first configuration to the second configuration if necessary, and then switch back to the first configuration once all oil has been discharged from the heat exchanger or exchanger. The first configuration corresponds to the main operating configuration of the supply system, while the second configuration is implemented on an exceptional and temporary basis.

[0051] This gas management method is therefore particularly suitable for floating structures for storing and / or transporting gas in a liquid state as described above.

[0052] According to the characteristics of the above method, when the first configuration is active, the return valve, control valve, regulating valve, control member, and regulating member are opened, while the recirculation valve, bypass valve, and bypass member are closed, and when the second configuration is active, the return valve, control valve, regulating valve, control member, and regulating member are closed, while the recirculation valve, bypass valve, and bypass member are opened.

[0053] According to the characteristics of the above method, the selection between the first configuration and the second configuration is determined by the pressure difference between the pressure measured by the first measuring member and the pressure measured by the second measuring member of the gas circulating in the return line at the levels of the inlet and outlet of the first heat exchanger and / or the levels of the inlet and outlet of the second heat exchanger.

[0054] Another characteristic of the above method is that the selection between the first configuration and the second configuration is determined by the temperature difference between the temperature measured by the first measuring device and the temperature measured by the second measuring device, of the gas circulating in the first supply circuit at the level of the inlet of the first heat exchanger and the gas circulating in the return line at the level of the outlet of the first heat exchanger, respectively, and / or the gas circulating in the first supply circuit at the level of the inlet of the second heat exchanger and the gas circulating in the return line at the level of the outlet of the second heat exchanger.

[0055] Calculating one or both of these difference values ​​at the level of one or both heat exchangers may result in a change in the configuration of the supply system. Valves and components are then relocated to modify the configuration. Brief explanation of the drawing

[0056] Other features and advantages of the present invention will become apparent, on the one hand, from the description that follows, and on the other hand, from a number of embodiments given as examples without limitation with reference to the attached schematic drawings. FIG. 1 is a schematic diagram of a first embodiment of a supply system according to the present invention. FIG. 2 illustrates the first configuration of a first embodiment of a supply system according to the present invention. FIG. 3 illustrates the second configuration of a first embodiment of a supply system according to the present invention. FIG. 4 is a schematic diagram of a second embodiment of a supply system according to the present invention. Specific details for implementing the invention

[0057] The terms "upstream" and "downstream" as used in the following description are used to describe the locations of elements within a circuit of a gas in a liquid or vapor state, and refer to the direction of circulation of the gas within the circuit.

[0058] FIG. 1 illustrates a first embodiment of a gas supply system (1) installed in a floating structure. The supply system (1) circulates gas, which may be in a liquid state, a vapor state, a two-phase state, or a supercritical state, from a storage and / or transport tank (8) to a high-pressure gas consumption device (4) and / or a low-pressure gas consumption device (5) to supply fuel to a high-pressure gas consumption device (4) and / or a low-pressure gas consumption device (5).

[0059] The above floating structure may be, for example, a vessel capable of storing and / or transporting gas in a liquid state. In this case, the supply system (1) may use the stored and / or transported gas to supply to a high-pressure gas consuming device (4), which may be, for example, a propulsion engine of the floating structure, and a low-pressure gas consuming device (5), which may be, for example, an electric generator supplying electricity to the floating structure.

[0060] In order to allow the gas contained in the tank (8) to be circulated to the high-pressure gas consumption device (4), the supply system (1) is provided with a first gas supply circuit (2). The first supply circuit (2) includes a first pumping device (9) located within the tank (8). The first pumping device (9) is used to pump gas in a liquid state and, in particular, to circulate it within the first supply circuit (2). By sucking in gas in a liquid state, the first pumping device (9) also raises the pressure of the gas to 6 bar to 17 bar.

[0061] The gas in a liquid state passes through the first heat exchanger (6) in a circulation direction from the tank (8) toward the high-pressure gas consumption device (4), is pumped by the second pumping device (10), and passes through the second heat exchanger (7). Details of the two heat exchangers (6, 7) will be described later.

[0062] After passing through the second heat exchanger (7), the gas is circulated to the high-pressure evaporator (11). The high-pressure evaporator (11) is used to change the state of the gas circulating in the first supply circuit (2) to enter a steam or supercritical state. This state makes the gas suitable for supply to the high-pressure gas consumption device (4). For example, the evaporation of the gas in a liquid state can occur by heat exchange with a heat transfer fluid at a sufficiently high temperature to evaporate the gas in a liquid state, in this case glycol water, seawater, or steam.

[0063] The gas pressure is increased when the second pumping device (10) pumps the gas in a liquid state. The second pumping device (10) increases the pressure of the gas in a liquid state to a value between 30 bar and 70 bar for use with liquefied petroleum gas, and preferably to a value between 150 bar and 400 bar for use with ethane, ethylene, or liquefied natural gas composed mainly of methane.

[0064] Thanks to the combination of the second pumping device (10) and the high-pressure evaporator (11), the gas has a pressure and condition suitable for the supply section of the high-pressure consumption device (4). This configuration eliminates the need to install a high-pressure compressor in the first supply circuit (2), which is expensive and generates strong vibrations.

[0065] Within the tank (8), some of the gas cargo naturally turns into a vapor state and can diffuse into the tank head (12). To prevent overpressure within the tank (8), the gas in the vapor state contained in the tank head (12) must be discharged. The first supply circuit (2) is configured to use gas in a liquid state to supply to the high-pressure gas consumption device (4).

[0066] The supply system (1) thus includes a second gas supply circuit (3) that supplies gas in a vapor state to a low-pressure gas consumption device (5) using gas in a vapor state. The second supply circuit (3) thus extends between the tank head (12) and the low-pressure gas consumption device (5). The second supply circuit (3) includes a compressor (13) for sucking in gas in a vapor state contained in the tank head (12). In addition to sucking in gas in a vapor state, the compressor (13) raises the pressure of the gas in a vapor state circulating in the second supply circuit (3) to a pressure between 6 bar and 20 bar in absolute pressure, so that the gas in a vapor state becomes a pressure compatible with the supply section of the low-pressure gas consumption device (5). Thus, the second supply circuit (3) enables the gas in a vapor state present in the tank head (12) to be supplied to the low-pressure gas consumption device (5) while regulating the pressure inside the tank (8) by sucking in the gas in a vapor state.

[0067] The presence of an excessive amount of gas in a vapor state within the tank head (12) leads to excess pressure within the tank (8). Therefore, it is necessary to discharge the gas in a vapor state to lower the pressure within the tank (8). The excess gas in a vapor state can then be removed, for example, by a burner (18). However, the supply system (1) according to the present invention includes a return line (14) connected to the second supply circuit (3) downstream of the compression device (13) with respect to the circulation direction of the gas in a vapor state circulating in the second supply circuit (3). Depending on the circulation direction of the gas in a vapor state circulating in the return line (14), the gas first passes through the second heat exchanger (7) and then passes through the first heat exchanger (6). Thus, heat exchange occurring within the first heat exchanger (6) and the second heat exchanger (7) takes place between the gas in a liquid state circulating in the first supply circuit (2) and the gas in a vapor state circulating in the return line (14). The purpose of this heat exchange is to re-liquefy the gas in the vapor state within the return line (14) so ​​that it passes through in a liquid state, and then return it to the tank (8) once this is completed.

[0068] The compression device (13) may be an oil compressor. The oil cools the compression device (13) and lubricates the moving parts of the compressor, thereby limiting wear on said moving parts and contributing to noise dissipation, which makes the oil compressor a desirable means of compressing gas into a vapor state. This type of compression device (13) includes a plurality of filters to prevent oil leakage from the compression device (13). However, this type of filtration is not perfect, and trace amounts of oil may leak from the compression device (13) carried by the gas flow in a vapor state.

[0069] A small amount of oil can then be circulated from the return line (14) to the second heat exchanger (7). The heat exchange operating within the first heat exchanger (6) and the second heat exchanger (7) cools the gas in a vapor state circulating in the return line (14). A small amount of oil also circulating in the return line (14) is thus cooled as well. However, the oil is contained in the tank (8) and has a much higher state change critical temperature than that of the gas circulating in the supply system (1). The very high cooling capacity of the heat exchangers (6, 7) thus causes a small amount of oil to solidify and condense within the heat exchangers (6, 7). Since the second heat exchanger (7) is the first place the oil circulating in the return line (14) passes, the possibility of oil solidification and condensation is highest within the return line. However, this phenomenon can also occur at the level of the first heat exchanger (6).

[0070] Although the amount of oil leaving the compressor (13) is small, the accumulation of oil that leaks from the compressor (13) over time and solidifies inside one or the other of the heat exchangers (6, 7) eventually becomes a problem, causing blockage within the heat exchangers (6, 7), cooling failure, and a significant pressure drop in the vaporized gas configured to circulate and re-liquefy in the return line (14). It is possible to replace the compressor (13) with an oil-free compressor, but this is limited and expensive.

[0071] To overcome this problem without the need to replace the compression device (13), the supply system (1) is provided with a recirculation branch (15) that starts at the level of a branch point (19) located on the return line (14) downstream of the second heat exchanger (7) and extends to the second supply circuit (3) upstream of the compression device (13). The recirculation branch (15) forms a loop between the second supply circuit (3) and the return line (14).

[0072] Thanks to the recirculation branch (15), the gas in a vapor state can be circulated in a loop through the heat exchangers (6, 7). The purpose is to gradually increase the temperature within the heat exchangers (6, 7) so that the oil aggregates accumulated therein are melted and returned to a liquid state before being carried by the gas flow and discharged from the heat exchangers (6, 7). The molten oil then circulates through the return line (14), then through the recirculation branch (15), and joins the second supply circuit (3). The oil then enters the compression device (13) and is filtered.

[0073] According to the first embodiment, the gas in a steam state circulates in a semi-closed loop within the heat exchanger (6, 7), that is, while circulating in the return line (14) and the heat exchanger (6, 7), the gas in a steam state is always discharged from the tank head (12), and the low-pressure gas consumption device (5) is always supplied with gas in a normal manner.

[0074] In order to raise the temperature inside the heat exchanger (6, 7) and to discharge the oil accumulated therein, the circulation of liquid gas in the first supply circuit (2) must be stopped inside the heat exchanger (6, 7). However, this must not lead to a interruption of the supply to the high-pressure gas consumption device (4).

[0075] Accordingly, the supply system (1) includes a first bypass branch (16) and a second bypass branch (17) that extend in parallel with the first heat exchanger (6) and the second heat exchanger (7), respectively, thereby bypassing the liquid gas circulation so that it continues to be supplied to the high-pressure gas consumption device (4) without passing through the heat exchangers (6, 7). Since the liquid gas circulation coming from the tank (8) and having a very low temperature is no longer in the heat exchangers (6, 7), the temperature can rise through the steam gas circulating in the loop.

[0076] Each bypass branch (16, 17) is connected to both sides of one of the heat exchangers (6, 7). In this way, the liquid gas circulating in the first supply circuit (2) is still pressurized by the second pumping device (10) to a pressure compatible with the requirements of the high-pressure gas consumption device (4), even though it bypasses the heat exchangers (6, 7). The liquid gas circulating in the first supply circuit (2) is also evaporated by the high-pressure evaporator (11). However, since the liquid gas has passed through the heat exchangers (6, 7) and has not been heated previously, its evaporation requires additional energy, so the configuration of the high-pressure evaporator (11) needs to be modified, particularly in terms of its energy input.

[0077] Accordingly, the supply system (1) according to the present invention can implement a management method that enables the supply system (1) to operate according to a first configuration in which the gas consumption device (4, 5) is supplied and the excess gas in a steam state is re-liquefied before being returned to the tank, and a second configuration in which the supply system (1) is operated intermittently and the purpose is to remove oil aggregates accumulated in the heat exchanger (6, 7).

[0078] To control the circulation of gas within the supply system (1) according to the configuration to be applied, the supply system (1) includes a recirculation valve (20) placed on the recirculation branch (15) and a return valve (21) placed on the return line (14) between the branch point (19) and the tank (8). The recirculation valve (20) allows or prevents the circulation of gas toward the second supply circuit (3), while the return valve (21) allows or prevents the circulation of gas toward the tank (8). Thus, it can be understood that one of these valves is open while the other is closed depending on the configuration implemented for the supply system (1).

[0079] Advantageously, the recirculation valve (20) also allows for the expansion of the gas circulating through the recirculation branch (15). Downstream of the recirculation branch (15), this expansion comes from the return line (14) and thus allows the gas previously compressed by the compressor (13) to be mixed at a pressure level equivalent to the gas coming directly from the tank (8).

[0080] The supply system (1) includes a bypass valve (22) as well as a control valve (23) and a regulating valve (24). The bypass valve (22) is positioned on the first bypass branch (16), whereas the control valve (23) and the regulating valve (24) correspond to a segment positioned in parallel with the first bypass branch (16) and are therefore positioned on the first segment (25) of the first supply circuit (2) passing through the first heat exchanger (6).

[0081] Therefore, it is understood that access to the first bypass branch (16) is controlled by the bypass valve (22). Access to the first segment (25) is controlled by the control valve (23) and the regulating valve (24). Advantageously, the control valve (23) and the regulating valve (24) are positioned on the first segment (25) on both sides of the first heat exchanger (6), with the control valve (23) upstream of the first heat exchanger (6) and the regulating valve (24) downstream of the first heat exchanger (6). The presence of the two valves means that the first heat exchanger (6) is completely isolated from the rest of the first supply circuit (2). Although the control valve (23) alone is sufficient to prevent the circulation of the liquid gas in the first heat exchanger (6), it is advantageous to also implement the regulating valve (24) to avoid the occurrence of a pressure difference that could lead to the evaporation of the liquid gas.

[0082] The supply system (1) also includes a bypass member (26) disposed on a second bypass branch (17), and a control member (27) and a regulating member (28) disposed on a second segment (29) of a first supply circuit (2) disposed in parallel with the second bypass branch (17). The control member (27) and the regulating member (28) are disposed on both sides of the second heat exchanger (7), with the control member (27) upstream of the second heat exchanger (7) and the regulating member (28) downstream of the second heat exchanger (7). The bypass member (26), the control member (27), and the regulating member (28) are corresponding parts of the bypass valve (22), the control valve (23), and the regulating valve (24), respectively, but interact at the level of the second heat exchanger (7). Thus, the operation of the members with respect to the valves is the same.

[0083] To detect whether it is necessary to implement a second configuration of the supply system (1) to remove oil present in the heat exchanger (6, 7), the supply system (1) includes a first measuring member (31), a second measuring member (32), a first measuring device (33), and a second measuring device (34).

[0084] The first measuring member (31) is configured to measure the pressure of the gas in a vapor state circulating in the return line (14) at the inlet of the first heat exchanger (6) and / or the inlet of the second heat exchanger (7), whereas the second measuring member (32) is configured to measure the pressure of the gas in a vapor state circulating in the return line (14) at the outlet of the first heat exchanger (6) and / or the outlet of the second heat exchanger (7). From these pressure measurements, a pressure difference can be inferred. Although there is always a pressure difference between the gas at the inlet and outlet of the heat exchangers (6, 7), if the pressure difference between the inlet and outlet of one of the heat exchangers (6, 7) is substantial, for example, from 40 mbar in the case of the first heat exchanger or from 200 mbar in the case of the second heat exchanger, this means that the gas is undergoing a substantial pressure drop as it passes through the heat exchangers (6, 7), which is potentially due to the accumulation of oil condensates inside. Accordingly, the second configuration of the supply system (1) can be implemented based on pressure measurement by the measuring member (31, 32). The second configuration can also be implemented after measuring the change in pressure difference calculated over time at at least one level of the heat exchangers (6, 7). As an example, a change in pressure difference exceeding 150%, preferably exceeding 100%, in relation to the pressure difference when there is no oil condensation in the heat exchanger is considered to be the moment when the accumulated oil needs to be discharged.

[0085] The first measuring device (33) and the second measuring device (34) are configured to measure the gas temperature. More specifically, the first measuring device (33) is configured to measure the temperature of the liquid gas circulating in the first supply circuit (2) at the inlet of the first heat exchanger (6) and / or the inlet of the second heat exchanger (7). The second measuring device (34) is configured to measure the temperature of the gas circulating in the return line (14) at the outlet of the first heat exchanger (6) and / or the outlet of the second heat exchanger (7).

[0086] The temperature difference between the temperature measured by the first measuring device (33) and the temperature measured by the second measuring device (34) is then calculated in the same heat exchanger. In other words, the temperature difference is calculated between the temperature of the liquid gas circulating in the first supply circuit (2) at the inlet of the first heat exchanger (6) or the second heat exchanger (7), respectively, and the temperature of the gas circulating in the return line (14) at the outlet of the first heat exchanger (6) or the second heat exchanger (7), respectively. If there is a significant temperature difference between the gas circulating in the first supply circuit (2) at the inlet of one of the heat exchangers (6, 7) and the gas circulating in the return line (14) at the outlet of the same heat exchanger (6, 7), this means that the heat treatment efficiency of the heat exchanger (6, 7) has been abnormally reduced, which may be due to the presence of oil aggregates in the heat exchanger (6, 7). The temperature difference considered necessary to implement the second configuration may be about 10°C, preferably 5°C. The second configuration may also be implemented after measuring the change in the temperature difference calculated over time at at least one level of the heat exchangers (6, 7).

[0087] Accordingly, the supply system (1) can be implemented in a second configuration based on the pressure difference or temperature difference inferred from the various measurements described above. The two difference values ​​can be calculated to limit the possibility of distorted measurements. Additionally, it should be noted that, as illustrated in FIGS. 1 to 3, the second measuring member (32) and the second measuring device (34) can be combined into a single unit.

[0088] FIG. 2 illustrates the circulation of gas through the supply system (1) when the supply system (1) is operated in the first configuration. In FIG. 2 and FIG. 3, solid lines indicate gas circulation, while dotted lines indicate the absence of gas circulation.

[0089] As previously mentioned, the first configuration consists of supplying the excess gas in a vapor state to the gas consumption device (4, 5) before re-liquefying it and returning it to the tank (8). In this first configuration, the return valve (21), control valve (23), regulating valve (24), control member (27), and regulating member (28) are open, while the recirculation valve (20), bypass valve (22), and bypass member (26) are closed.

[0090] According to this first configuration, the liquid gas contained in the tank (8) is pumped by the first pumping device (9) and circulated within the first supply circuit (2). The liquid gas passes through the first heat exchanger (6), is pumped by the second pumping device (10) to a pressure compatible with the high-pressure gas consumption device (4), passes through the second heat exchanger (7), and is evaporated by the high-pressure evaporator (11) and then supplied to the high-pressure consumption device (4).

[0091] As the liquid gas passes through the heat exchanger (6, 7), its temperature rises due to heat exchange with the steam gas circulating in the return line (14), which facilitates its subsequent evaporation.

[0092] The gas in a vapor state present in the tank head (12) is drawn into the second supply circuit (3), compressed by the compression device (13), and supplied to the low-pressure gas consumption device (5). The excess gas in a vapor state, i.e., the excess gas in a vapor state in relation to the supply requirements of the low-pressure gas consumption device (5), is circulated in the return line (14) and passes through the second heat exchanger (7) and then the first heat exchanger (6). The gas in a vapor state is pre-cooled in the second heat exchanger (7) and finally re-liquefied in the first heat exchanger (6). The re-liquefied gas is then returned to the tank (8).

[0093] As described above, after compression by the compression device (13), a small amount of oil is carried by a gas in a vapor state and exits the compression device (13). When this small amount of oil circulates within the return line (14), its passage through either of the heat exchangers (6, 7) can cool it and solidify it within the heat exchangers (6, 7).

[0094] FIG. 3 illustrates the circulation of gas through the supply system (1) when the supply system (1) is operated in a second configuration. As previously mentioned, this second configuration is implemented following the accumulation of oil aggregates in either of the heat exchangers (6, 7), and these aggregates must be removed to maintain the accurate operation of the supply system (1). These accumulations can be detected by the first measuring member (31) and the second measuring member (32) and / or the first measuring device (33) and the second measuring device (34).

[0095] In this second configuration, the return valve (21), control valve (23), control valve (24), control member (27) and control member (28) are closed, and the recirculation valve (20), bypass valve (22) and bypass member (26) are opened.

[0096] Since the purpose is to raise the temperature inside the heat exchanger (6, 7), there is no problem with circulating the gas in a liquid state inside it.

[0097] However, the high-pressure gas consumption device (4) must be continuously supplied. In this way, the liquid gas contained in the tank (8) is pumped by the first pumping device (9) and circulated within the first supply circuit (2). The liquid gas circulates through the first bypass branch (16) to bypass the first heat exchanger (6), is pumped by the second pumping device (10) to rise to a pressure compatible with the high-pressure gas consumption device (4), and also circulates through the second bypass branch (17) to bypass the second heat exchanger (7), and is supplied to the high-pressure consuming device (4) after being evaporated by the high-pressure evaporator (11). Even if the liquid gas is not cooled because it bypasses the heat exchangers (6, 7), the high-pressure evaporator (11) can evaporate the liquid gas.

[0098] Gas in a vapor state is drawn from the tank head (12) by the compressor (13) and circulated in the second supply circuit (3). In the second configuration, the low-pressure gas consumption device (5) must also be supplied with gas. As described above, the first embodiment of the supply system (1) implements the second configuration as a semi-closed loop. Thus, some of the gas in a vapor state can be supplied to the low-pressure gas consumption device (5) if necessary, that is, the gas leaving the compressor (13) is simultaneously distributed toward the low-pressure gas consumption device (5) and into the return line (14).

[0099] The gas in a vapor state also circulates in the return line (14), passes through the second heat exchanger (7), and then passes through the first heat exchanger (6). Since the gas in a liquid state does not circulate in the heat exchangers (6, 7), the gas in a vapor state is not re-liquefied on the one hand, and on the other hand, causes an increase in temperature within the heat exchangers (6, 7). When leaving the first heat exchanger (6), the gas in a vapor state does not return to the tank (8) but circulates in the recirculation branch (15), is compressed again by the compressor (13), recirculated in the return line (14), and passes through the heat exchangers (6, 7) once again. The circulation of the gas in a vapor state within the loop passing through the heat exchangers (6, 7) increases the temperature inside. The oil condensate is then melted, and the oil is carried along by the gas in a vapor state and eventually discharged from the heat exchangers (6, 7). The oil is also returned to the compression device (13) through the recirculation branch (15), and then collected by the filtering means of the compression device (13).

[0100] The second operating mode is carried out until the oil in the heat exchangers (6, 7) is completely removed. It is possible to determine whether the oil has been discharged by measuring the pressure difference between the first measuring member (31) and the second measuring member (32) at the level of each heat exchanger (6, 7). Once this is completed, the supply system (1) can be operated again in the first configuration. During the implementation of the second configuration, the low-pressure gas consumption device (5) can always be supplied by the gas in a vapor state circulating in the second supply circuit (3). Access to the tank vessel (8) for drawing the gas in a vapor state present in the tank head (12) is also opened when the second configuration is used.

[0101] FIG. 4 illustrates a second embodiment of a supply system (1) according to the present invention. The second embodiment differs from the first embodiment in that, when the second configuration is implemented, the gas in a steam state circulates in a completely closed loop within the heat exchangers (6, 7).

[0102] However, since the supply to the low-pressure gas consumption device (5) must be maintained, the second embodiment of the supply system (1) includes an auxiliary supply branch (35) that provides a fluid connection between the tank (8) and the low-pressure gas consumption device (5) so that the low-pressure gas consumption device (5) can be supplied despite the closed loop implemented through the second supply circuit (3), the return line (14), and the recirculation branch (15).

[0103] The auxiliary supply branch (35) includes a compression member (36) capable of drawing in the gas in a vapor state present in the tank head (12) and raising it to a pressure compatible with the requirements of the low-pressure gas consumption device (5). Thus, when the gas in a vapor state is circulated within a closed loop after being circulated by the compression device (13), it is the compression member (36) that draws in the gas in a vapor state contained in the tank head (12) to supply it to the low-pressure gas consumption device (5).

[0104] Additionally, as illustrated in FIG. 4, the supply system (1) includes a first auxiliary valve (37) disposed on a second supply circuit (3) between the inlet of the auxiliary supply branch (35) and the outlet of the recirculation branch. The supply system (1) also includes a second auxiliary valve (38) disposed on a second supply circuit (3) between the connection of the return line (14) and the outlet of the auxiliary supply branch (35).

[0105] The first auxiliary valve (37) and the second auxiliary valve (38) completely isolate a closed loop, including a portion of the second supply circuit, a return line (14), and a recirculation branch (15), from the supply portion of the low-pressure gas consuming device (5) provided particularly by the auxiliary supply branch (35). This configuration prevents any undesirable thermal phenomena between the flow of gas containing molten oil coming from the return line (14) and the gas going directly out from the tank head (12) having a much lower temperature, for example, freezing of the oil upon contact with the low-temperature gas in a vapor state coming from the tank head (12).

[0106] Since the remainder of the structural and functional characteristics of the second embodiment are the same as those of the first embodiment, reference is made to the description of FIGS. 1 to 3 for elements common to both embodiments. Of course, the present invention is not limited to the embodiments just described, and many adjustments may be made to these embodiments without departing from the scope of the present invention.

[0107] The present invention, as just described, provides a gas supply system for two gas consuming devices that achieves the above objective, allows excess gas in a vapor state to be re-liquefied, and also allows oil accumulated in the heat exchanger of the supply system to be discharged. Variations not described herein may be implemented without departing from the context of the present invention, provided that they include the supply system according to the present invention.

Claims

Claim 1 A supply system (1) for supplying gas to at least one high-pressure gas consuming device (4) and at least one low-pressure gas consuming device (5) of a floating structure comprising at least one tank (8) configured to receive gas, comprising: at least one first supply circuit (2) configured to supply gas to the high-pressure gas consuming device (4) and comprising at least one first pumping device (9) configured to pump gas taken from the tank (8) in a liquid state; at least one high-pressure evaporator (11) configured to evaporate the gas circulating in the first supply circuit (2); at least one second supply circuit (3) configured to supply gas to the low-pressure gas consuming device (5) and comprising at least one compression device (13) configured to compress gas taken from the tank (8) in a vapor state to a pressure compatible with the requirements of the low-pressure gas consuming device (5); and at least one gas return line (14) connected to the second supply circuit (3) downstream of the compression device (13) and extending to the tank (8). — The supply system (1) comprises at least one first heat exchanger (6) and at least one second heat exchanger (7), each configured to operate heat exchange between a gas in a steam state circulating in the return line (14) and a gas in a liquid state circulating in the first supply circuit (2), and the first supply circuit (2) comprises a second pumping device (10) inserted between the first heat exchanger (6) and the second heat exchanger (7). — In a supply system (1), the supply system (1) comprises a recirculation branch (15) connected at an inlet to a branch point (19) disposed on the return line (14) between the first heat exchanger (6) and the tank (8), and the recirculation branch (15) comprises an outlet connected to the second supply circuit (3) between the tank (8) and the compression device (13).A supply system characterized in that the first supply circuit (2) comprises a first bypass branch (16) arranged in parallel with a first segment (25) of the first supply circuit (2) passing through the first heat exchanger (6), and a second bypass branch (17) arranged in parallel with a second segment (29) of the first supply circuit (2) passing through the second heat exchanger (7). Claim 2 A supply system according to claim 1, comprising a recirculation valve (20) disposed on the recirculation branch (15) and a return valve (21) disposed on the return line (14) between the branch point (19) and the tank (8). Claim 3 A supply system according to claim 1 or 2, comprising a bypass valve (22) disposed on the first bypass branch (16) and a control valve (23) disposed on the first segment (25) of the first supply circuit (2). Claim 4 In claim 3, the control valve (23) is positioned on a first segment (25) upstream of the first heat exchanger (6), and the supply system (1) comprises a control valve (24) positioned on a first segment (25) downstream of the first heat exchanger (6). Claim 5 A supply system according to any one of claims 1 to 4, comprising a bypass member (26) disposed on the second bypass branch (17) and a control member (27) disposed on the second segment (29) of the first supply circuit (2). Claim 6 In claim 5, the control member (27) is positioned on a second segment (29) upstream of the second heat exchanger (7), and the supply system (1) comprises a control member (28) positioned on a second segment (29) downstream of the second heat exchanger (7). Claim 7 A supply system comprising a first measuring member (31) and a second measuring member (32) configured to measure the pressure of the gas circulating in the return line (14) at the inlet and outlet of the first heat exchanger (6) and / or the inlet and outlet of the second heat exchanger (7), respectively, in any one of claims 1 to 6. Claim 8 A supply system comprising a first measuring device (33) and a second measuring device (34) configured to measure, respectively, the temperature of a gas circulating in a first supply circuit (2) at the inlet of the first heat exchanger (6) and the temperature of a gas circulating in a return line (14) at the outlet of the first heat exchanger (6) and / or the temperature of a gas circulating in a first supply circuit (2) at the inlet of the second heat exchanger (7) and the temperature of a gas circulating in a return line (14) at the outlet of the second heat exchanger (7). Claim 9 A supply system according to any one of claims 1 to 8, comprising an auxiliary supply branch (35) connected at an inlet to a second supply circuit (3) between the tank (8) and the outlet of the recirculation branch (15), wherein the auxiliary supply branch (35) comprises an outlet connected to a second supply circuit (3) between a connection to a return line (14) and a low-pressure gas consumption device (5), and wherein the auxiliary supply branch (35) comprises a compression member (36). Claim 10 In claim 9, the second supply circuit (3) comprises a first auxiliary valve (37) positioned between the inlet of the auxiliary supply branch (35) and the outlet of the recirculation branch (15), and a second auxiliary valve (38) positioned between the connection to the return line (14) and the outlet of the auxiliary supply branch (35). Claim 11 A supply system according to any one of claims 1 to 10, wherein the first pumping device (9) is configured to increase the pressure of the liquid gas to a value between 6 bar and 17 bar, and the second pumping device (10) is configured to increase the pressure of the liquid gas to a value between 30 bar and 400 bar. Claim 12 A supply system configured such that, in any one of claims 1 to 11, the compression device (13) increases the pressure of the gas to a value between 6 bar and 20 bar absolute pressure. Claim 13 A floating structure for storing and / or transporting gas in a liquid state, comprising at least one tank (8) for gas in a liquid state, at least one high-pressure gas consuming device (4), at least one low-pressure gas consuming device (5), and at least one system (1) for supplying gas to the devices described in any one of claims 1 to 12. Claim 14 A gas management method implemented by a supply system (1) described in any one of claims 1 to 12, used within a floating structure comprising at least one tank (8) configured to receive gas, wherein during the method: · in a first configuration, the gas is circulated in a liquid state in a first supply circuit (2) within a first heat exchanger (6) and a second heat exchanger (7), and the gas in a vapor state is circulated to the tank (8) within a return line (14); · according to a second configuration, the gas in a liquid state is circulated in a first supply circuit (2) within a first bypass branch (16) and a second bypass branch (17), and the gas in a vapor state is circulated within a recirculation branch (15). Claim 15 A gas management method according to claim 14, implemented by a supply system (1) described in claims 2, 4 and 6, wherein when the first configuration is active, the return valve (21), control valve (23), control valve (24), control member (27) and control member (28) are open, while the recirculation valve (20), bypass valve (22) and bypass member (26) are closed, and when the second configuration is active, the return valve (21), control valve (23), control valve (24), control member (27) and control member (28) are closed, while the recirculation valve (20), bypass valve (22) and bypass member (26) are open. Claim 16 A gas management method according to claim 14 or 15, implemented by the supply system (1) described in claim 7, wherein the selection between the first configuration and the second configuration is determined by the pressure difference between the pressure measured by the first measuring member (31) and the pressure measured by the second measuring member (32) of the gas circulating in the return line (14) at the levels of the inlet and outlet of the first heat exchanger (6) and / or the inlet and outlet of the second heat exchanger (7). Claim 17 A gas management method in which, in any one of claims 14 to 16, the supply system (1) described in claim 8 is implemented, and the selection between the first configuration and the second configuration is determined according to the temperature difference between the temperature measured by the first measuring device (33) and the temperature measured by the second measuring device (34), of the gas circulating in the first supply circuit (2) at the level of the inlet of the first heat exchanger (6) and the gas circulating in the return line (14) at the level of the outlet of the first heat exchanger (6), respectively.

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