Gas supply system for a floating structure

Abstract

Gas supply system for a floating structure. The present invention relates to a gas supply system (1) for a high-pressure gas-consuming appliance (4) and a low-pressure gas-consuming appliance (5) of a floating structure, comprising: a first supply circuit (2), a high-pressure evaporator (11), a second supply circuit (3), a gas return line (14), the supply system (1) comprising a first heat exchanger (6) and a second heat exchanger (7), the first supply circuit (2) comprising a second pumping device (10) interposed between the first heat exchanger (6) and the second heat exchanger (7), characterized in that the supply system (1) comprises a recirculation branch (15), the first supply circuit (2) comprising a first bypass branch (16) and a second bypass branch (17). (Figure 1)

Description

Title of the invention: Gas supply system for 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 consuming appliances included within such floating structures, as well as a method for managing such a system.

[0002] During a journey undertaken by a floating structure comprising a tank of liquid gas intended for consumption and / or delivery to a destination point, said floating structure may be capable of using at least a portion of said liquid gas to power at least one of its engines, via a gas supply system. This is the case for ships equipped with a high-pressure propulsion engine of the ME-GI type. In order to power this type of engine, the gas must be compressed to very high pressure by special compressors capable of compressing the gas up to 300 bar absolute, but such compressors are expensive, generate significant maintenance costs, and induce vibrations within the ship.

[0003] An alternative to installing these high-pressure compressors is to vaporize the gas in its liquid state at 300 bar absolute, notably using a high-pressure pumping device, before it is sent to the propulsion engine. Since such a solution does not allow for the removal of the gas in its vapor state (or BOG, which stands for "Boil-Off Gas") that naturally forms within a tank containing at least part of the cargo, a low-pressure compression device is then installed to supply an auxiliary engine capable of consuming the gas in vapor form at low pressure.

[0004] It is also known to recirculate, downstream of the compression device, the excess gas in vapor form and to reliquefy it by means of one or more heat exchanges, operated by one or more heat exchangers, between the gas in liquid state intended to supply the high-pressure propulsion engine and the gas in vapor state intended to be reliquefied.

[0005] A drawback may arise in this power supply system if the compression device used is an oil compressor, which is the case in the majority of such system arrangements. Although oil compressors are equipped with filtration means preventing oil from leaving the compressor and circulating within the power supply system, a small amount of oil still manages to escape from the compressor and subsequently circulate through the branches of the power supply system circuit.

[0006] If the oil subsequently circulates within the aforementioned heat exchanger(s), the oil is cooled and may solidify within the heat exchanger. Over time, the solidified oil accumulates within at least one heat exchanger, clogging it and thus severely impairing its heat transfer capacity. It is possible to replace the compressor with an oil-free compressor, but such a replacement is complex and costly.

[0007] The present invention addresses this problem and, as such, proposes a gas supply system for at least one high-pressure gas-consuming appliance and at least one low-pressure 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 gas supply circuit for the high-pressure gas-consuming appliance, including at least one first pumping device configured to pump the gas drawn from the tank in liquid form, - at least one high-pressure evaporator configured to evaporate the gas circulating in the first supply circuit, - at least one second gas supply circuit for the low-pressure gas-consuming appliance, including at least one compression device configured to compress gas taken from the tank in vapor form to a pressure compatible with the needs of the low-pressure gas-consuming appliance, - at least one gas return line connected to the second supply circuit downstream of the compression device and extending to the tank, the supply system comprising at least one first heat exchanger and at least one second heat exchanger each configured to operate a heat exchange between the gas in vapor state circulating in the return line and the gas in liquid state circulating in the first supply circuit, the first supply circuit comprising a second pumping device interposed between the first heat exchanger and the second heat exchanger,

[0008] characterized in that the supply system comprises a recirculation branch connected at its inlet to a divergence point disposed on the return line between the first heat exchanger and the tank, the recirculation branch comprising an outlet connected to the second supply circuit between the tank and the compression device, the first supply circuit comprising a first bypass branch arranged in parallel with a first portion of the first supply circuit passing through the first heat exchanger and a second bypass branch arranged in parallel with a second portion of the first through-feed supply circuit of the second heat exchanger.

[0009] The supply system, in addition to being able to supply gas-consuming devices while operating a reliquefaction of excess gas in vapor state, is also able to implement a configuration ensuring the elimination of oil that has accumulated within one or more of the heat exchangers.

[0010] To achieve this, the recirculation branch forms a vapor gas loop between the second supply circuit and the return line so that the vapor gas circulates in a loop within the heat exchangers. Such a loop can be semi-closed or fully closed, depending on an embodiment of the supply system according to the invention. In the case of a semi-closed loop, in addition to ensuring a closed-loop circulation of the vapor gas in the heat exchangers, the vapor gas contained in the tank is always drawn by the compression device to circulate in the second supply circuit, and the low-pressure gas-consuming device is always supplied. Such a configuration corresponds to a first embodiment of the supply system according to the invention.The circulation of gas in vapor form within the heat exchangers causes a temperature rise within them and the melting of the oil that has accumulated there. This oil can then be removed by being carried away by the flow of gas in vapor form. The oil then flows to the compression device where it is filtered and stored.

[0011] To ensure the heat exchangers reach the required temperature, only vaporized gas should circulate within them, as the liquid gas circulating in the first supply circuit is at too low a temperature to guarantee such a temperature increase. However, the supply to the high-pressure gas-consuming device must be maintained, including during the melting of the oil contained in the heat exchangers. The bypass branches thus ensure the gas supply to the high-pressure gas-consuming device without the liquid gas interfering with the heat exchanger temperature increase. Initially, the treatment of the liquid gas is handled solely by the second pumping device, and the high-pressure evaporator alone evaporates the liquid gas to ensure that the gas meets the requirements of the high-pressure gas-consuming device.

[0012] As previously mentioned, the first gas supply circuit provides the fuel requirements for the high-pressure gas-consuming device. This device could, for example, be the propulsion system for the floating structure, such as an ME-GI engine. The first supply circuit extends from the tank to the high-pressure gas-consuming device. The first device The pumping station is installed at the bottom of the tank and ensures the pumping of the gas in liquid state so that it can circulate in the first supply circuit.

[0013] The second pumping device increases the pressure of the liquid gas circulating in the first supply circuit, so that it has a pressure suitable for supplying the high-pressure gas-consuming equipment. Positioning the second pumping device between the two heat exchangers is particularly advantageous because it ensures both efficient heat treatment of the vapor gas circulating in the return line by the liquid gas circulating in the first supply circuit, while preventing premature evaporation of said liquid gas that could damage the second pumping device. Even when the liquid gas bypasses the heat exchangers, it continues to be pumped by the second pumping device.

[0014] Since the gas must be in a vapor state to supply the high-pressure gas-consuming device, the high-pressure evaporator ensures the evaporation of the gas before it is supplied to the high-pressure gas-consuming device. The high-pressure evaporator is the site of a heat exchange between the gas in a liquid state circulating in the first supply circuit and a heat transfer fluid, for example, glycol water, seawater, or steam. The latter must be at a sufficiently high temperature to induce a change of state in the gas so that it transitions to a vapor or supercritical state to supply the high-pressure gas-consuming device, whether or not the gas in a liquid state has previously passed through the heat exchangers.

[0015] In a reliquefaction configuration of excess gas in the vapor state, before the liquid gas circulating in the first feed circuit is vaporized by the high-pressure evaporator, the liquid gas passes through the first heat exchanger, then the second heat exchanger. For this purpose, the first and second heat exchangers are connected by a section of the first feed circuit so that the liquid gas can pass through the two heat exchangers successively, this section advantageously including the second pumping device. The temperature of the liquid gas thus tends to increase before it passes through the high-pressure evaporator. Therefore, the gas circulating in the first feed circuit can be in a two-phase state at the outlet of the second heat exchanger.

[0016] Generally, the gas contained in the tank can naturally, or be forced by the floating structure, into a vapor state. The gas within the tank that changes to a vapor state must be evacuated in order to avoid creating overpressure within the tank.

[0017] This function is performed by the 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 latter may, for example, be an auxiliary motor such as an electric generator. The compression device located on the second supply circuit is responsible for drawing in the gas present in the tank's headspace in order to both supply the low-pressure gas-consuming device and regulate the pressure within the tank. Such a compression device may be an oil compressor.

[0018] At the outlet of the compression device, the gas in vapor form can supply the low-pressure gas-consuming appliance, or flow through the return line if the low-pressure gas-consuming appliance does not require a fuel supply or if the quantity of gas in vapor form exceeds the supply requirement of the low-pressure gas-consuming appliance. Since the return line is connected downstream of the compression device, the gas in vapor form drawn in by said compression device can therefore flow through it, as can a minute quantity of oil that may have escaped from the compression device if the latter is oil-cooled.

[0019] The vapor gas flowing in the return line first passes through the second heat exchanger, then the first heat exchanger, before joining the first supply circuit. Through the heat exchange occurring between the liquid gas flowing in the first supply circuit and the vapor gas flowing in the return line, the temperature of the vapor gas decreases as it passes through the heat exchangers, until the gas reliquefies and returns to a liquid state substantially at the outlet of the first heat exchanger and can then flow to the tank. Traces of oil accompanying the vapor gas also pass through the heat exchangers and cool and solidify within one or the other of said heat exchangers.Although the amount of oil escaping from the compression device is minimal, the accumulation of solidified oil over time eventually impairs the proper functioning of the fuel system.

[0020] As mentioned previously, the recirculation branch forms a loop so that the gas can circulate from the return line to the second supply circuit. This allows the gas in vapor form to circulate multiple times within the heat exchangers, while the circulation of gas in liquid form is interrupted in these same heat exchangers. Since the gas in vapor form is at a higher temperature, this causes a temperature rise within the heat exchangers, melting any oil aggregates that have accumulated there. and evacuating them. Once the oil has been completely evacuated from the heat exchangers, the configuration of the feed system can again be modified in order to be able to implement the reliquefaction of the excess gas in the vapor state again.

[0021] According to one feature of the invention, the supply system comprises a recirculation valve disposed on the recirculation branch and a return valve disposed on the return line between the divergence point and the tank. The valves are capable of switching between an open position and a closed position in order to respectively allow or prevent the circulation of gas in the branch or circuit under consideration. The return valve controls the return of the gas to the tank after its reliquefaction. The recirculation valve, for its part, controls the circulation of the gas in the vapor state so that it circulates in a loop through the heat exchangers to increase their temperature. Thus, when one of the valves, the recirculation valve or the return valve, is open, the other valve is necessarily closed.

[0022] In the case of a closed-loop circulation within the heat exchangers according to a semi-closed loop, i.e., according to the first embodiment, the recirculation valve also ensures an expansion of the gas in the vapor state that has previously been compressed by the compression device. This expansion makes it possible to equalize the pressure between the gas in the vapor state coming from the return line and the gas in the vapor state exiting directly from the tank.

[0023] According to one feature of the invention, the supply system comprises a bypass valve disposed on the first bypass branch and a control valve disposed on the first portion of the first supply circuit. The control valve and the bypass valve allow the gas in its liquid state circulating in the first supply circuit to pass through the first heat exchanger or to bypass it so that it heats up in order to melt the oil that has accumulated there. As with the valves described above, the control valve and the bypass valve are capable of switching between an open position and a closed position in order to respectively allow or prevent the flow of gas in the branch or circuit in question.

[0024] According to one feature of the invention, the control valve is located on the first upstream portion of the first heat exchanger, the supply system comprising a regulating valve located on the first downstream portion of the first heat exchanger. Advantageously, this allows the first heat exchanger to be completely isolated from the flow of liquid gas within the first supply circuit. This prevents traces of liquid gas from circulating within the first heat exchanger and disrupting its temperature rise and / or from evaporating there and generating an undesirable pressure increase. as desired. Thus, advantageously, the control valve and the regulating valve are opened simultaneously or closed simultaneously.

[0025] According to one feature of the invention, the power supply system includes a bypass element disposed on the second bypass branch and a control element disposed on the second portion of the first power supply circuit.

[0026] According to another feature of the invention, the control element is disposed on the second portion upstream of the second heat exchanger, the supply system comprising a regulating element disposed on the second portion downstream of the second heat exchanger.

[0027] The bypass device, the control device, and the regulating device are the counterparts of the eponymous valves described previously, but applied to the second heat exchanger instead of the first heat exchanger. The operation of the bypass device, the control device, and the regulating device is therefore respectively identical to the operation of the bypass valve, the control valve, and the regulating valve.

[0028] According to one feature of the invention, the feed system comprises a first measuring element and a second measuring element configured to respectively measure the pressure of the gas flowing in the return line at the inlet and outlet of the first heat exchanger and / or at the inlet and outlet of the second heat exchanger. The measuring elements make it possible to detect whether it is time to operate the feed system in order to eliminate any potential oil aggregates that may have accumulated in one or both of the heat exchangers.

[0029] Such a need can be detected by measuring the pressure drop of the gas in the vapor state at the outlet of at least one of the heat exchangers compared to its pressure before entering that same heat exchanger. The pressure drop manifests as a pressure differential of the gas between its inlet and outlet at least one of the heat exchangers. If the pressure differential is high, for example, from 40 mbar for the first heat exchanger or from 200 mbar for the second heat exchanger, this means that oil aggregates are present in significant quantities and that they are impairing the proper functioning of the supply system. Such a pressure differential can be measured at one or both heat exchangers simultaneously.

[0030] It may also be advantageous to calculate the evolution of the pressure differential over time in order to determine at what point it is advisable to implement the removal of the oil accumulated in at least one of the heat exchangers. For example, a variation in the pressure differential of more than 150%, preferably more than 100% compared to the pressure differential when the heat exchangers do not have oil aggregates, is considered such as the moment when the evacuation of accumulated oil is necessary.

[0031] According to one feature of the invention, the supply system comprises a first measuring device and a second measuring device configured to respectively measure a temperature of the gas flowing in the first supply circuit at the inlet of the first heat exchanger and of the gas flowing in the return line at the outlet of the first heat exchanger and / or of the gas flowing in the first supply circuit at the inlet of the second heat exchanger and of the gas flowing in the return line at the outlet of the second heat exchanger.

[0032] As an alternative or supplement to pressure measurement by the measuring devices, the need to remove oil aggregates present in one or both heat exchangers can be detected using a temperature differential between the temperature of the liquid gas flowing in the first supply circuit at the inlet of one of the heat exchangers and the temperature of the gas flowing in the return line at the outlet of the same heat exchanger. The temperature differential is therefore calculated from measurements taken for a single heat exchanger. An excessively high differential between these two temperatures indicates that the heat exchange in the heat exchanger in question is not sufficiently efficient due to an excessive amount of oil aggregates present within it.The temperature differential from which it is considered necessary to proceed with oil evacuation can be on the order of 10°C, preferably 5°C.

[0033] It may also be advantageous to calculate an evolution of the temperature differential over time in order to determine from what moment it is appropriate to implement the evacuation of the oil accumulated within at least one of the heat exchangers.

[0034] The previously described pressure differential and temperature differential measurements can be implemented simultaneously to perform a dual check of the need to remove oil aggregates from one or both heat exchangers. During such an operation, the pressure differential can be monitored over time to verify whether the removal of oil aggregates is proceeding correctly and at what point the operation can be stopped.

[0035] According to one feature of the invention, the supply system comprises an auxiliary supply branch connected at its inlet to the second supply circuit between the tank and the outlet of the recirculation branch, the auxiliary supply branch comprising an outlet connected to the second supply circuit between the connection to the return line and the low-pressure gas-consuming device, the auxiliary supply branch comprising a compression element. Such a configuration constitutes a second embodiment according to the invention.

[0036] In this second embodiment, the gas in the vapor state circulates within the heat exchangers in a completely closed loop. It is understood that the evacuation of the gas in the vapor state from the tank and the supply of the low-pressure gas-consuming device are carried out via the auxiliary supply branch, while the heat exchangers increase in temperature over time thanks to a defined and constant quantity of gas in the vapor state that circulates in a loop between the second supply circuit and the return line.

[0037] According to one feature of the invention, the second supply circuit comprises 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. Also according to the second embodiment of the supply system according to the invention, the first and second auxiliary valves allow for the complete isolation of the vapor gas loop, ensuring the temperature increase of the heat exchangers. Thus, the tank and the low-pressure gas-consuming equipment are only connected via the auxiliary supply branch. The auxiliary valves are therefore in the closed position when it is necessary to drain the oil accumulated in at least one of the heat exchangers.

[0038] According to one feature of the invention, the first pumping device is configured to raise the pressure of the gas in the liquid state to a value between 6 and 17 bar, and the second pumping device is configured to raise the pressure of the gas in the liquid state to a value between 30 and 400 bar. The pressure increase of the gas by the second pumping device depends on the type of gas being transported and / or stored. Thus, the pressure of the gas in the liquid state is raised to a value between 30 and 400 bar absolute, particularly for use with ammonia or hydrogen, between 30 and 70 bar absolute for use with liquefied petroleum gas, and preferably between 150 and 400 bar absolute for use with ethane, ethylene, or liquefied natural gas consisting mainly of methane.

[0039] According to one feature of the invention, the compression device is configured to raise the gas pressure to a value between 6 and 20 absolute bars.

[0040] The invention also covers a floating structure for the storage and / or transport of gas in liquid state, comprising at least one tank of gas in liquid state, at least one high-pressure gas-consuming device, at least one low-pressure gas-consuming device and at least one gas supply system for these devices as described above.

[0041] The invention also covers a gas management method implemented by a feed system as described above, in which: - The gas is circulated in liquid form in the first supply circuit within the first heat exchanger and the second heat exchanger, and the gas is circulated in vapor form within the return line to the tank according to a first configuration, - the gas is circulated in liquid form in the first supply circuit within the first bypass branch and the second bypass branch and the gas is circulated in vapor form within the recirculation branch according to a second configuration.

[0042] It follows from the above that the first configuration corresponds to the configuration where the excess gas in vapor form is reliquefied before returning to the tank using the gas in liquid form circulating in the first feed circuit and the heat exchangers, while the second configuration corresponds to the configuration where the gas in vapor form circulates in a loop within the heat exchangers in order to create a temperature rise ensuring the removal of oil aggregates that have accumulated within said heat exchangers. The feed system can switch from the first configuration to the second configuration if necessary, and then back to the first configuration once the oil has been completely removed from the heat exchanger(s).The first configuration corresponds to the main operating configuration of the power system, while the second configuration is implemented on an exceptional and temporary basis.

[0043] According to one feature of the process, the return valve, the control valve, the regulating valve, the control element and the regulating element are open while the recirculation valve, the bypass valve and the bypass element are closed when the first configuration is active, the return valve, the control valve, the regulating valve, the control element and the regulating element being closed while the recirculation valve, the bypass valve and the bypass element being open when the second configuration is active.

[0044] According to a feature of the process, a selection between the first configuration and the second configuration is dependent on a pressure difference between the pressure measured by the first measuring element and the pressure measured by the second measuring element of the gas circulating in the return line at the inlet and outlet of the first heat exchanger and / or at the inlet and outlet of the second heat exchanger.

[0045] According to another feature of the process, a selection between the first configuration and the second configuration is dependent on a temperature difference between the temperature measured by the first measuring device and the temperature measured by the second measuring device respectively of the gas circulating in the first supply circuit at the inlet of the first heat exchanger and of the gas circulating in the return line at the outlet of the first heat exchanger and / or of the gas circulating in the first supply circuit at the inlet of the second heat exchanger and of the gas circulating in the return line at the outlet of the second heat exchanger.

[0046] Calculating one or both of these differentials at one or both heat exchangers can lead to a change in the configuration of the supply system. The valves and components then change position to modify the configuration.

[0047] 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 of embodiments given with reference to the accompanying schematic drawings on the other hand, in which:

[0048] [Fig. 1] is a schematic representation of a first embodiment of a power supply system according to the invention,

[0049] [Fig.2] illustrates a first configuration of the first embodiment of the power supply system according to the invention,

[0050] [Fig.3] illustrates a second configuration of the first embodiment of the power supply system according to the invention,

[0051] [Fig.4] is a schematic representation of a second embodiment of the power supply system according to the invention.

[0052] The terms "upstream" and "downstream" used in the following description are used to express positions of elements within circuits of gas in liquid or vapor state and refer to the direction of flow of said gas within said circuit.

[0053] Fig. 1 represents a first embodiment of a gas supply system 1 arranged on a floating structure. The supply system 1 allows gas to circulate, which may be in liquid, vapor, two-phase or supercritical state, from a storage and / or transport tank 8 to a high-pressure gas-consuming device 4 and / or a low-pressure gas-consuming device 5, in order to supply them with fuel.

[0054] Said floating structure may, for example, be a vessel capable of storing and / or transporting gas in liquid form. The supply system 1 is in this case capable of using the gas in liquid form that the floating structure stores and / or transports to supply the high-pressure gas-consuming device 4, which may, for example, be a propulsion engine, and the low-pressure gas-consuming device 5, which may, for example, be an electric generator supplying the floating structure in electricity.

[0055] To ensure the circulation of the gas contained in the tank 8 to the high-pressure gas-consuming 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 allows the gas to be pumped in its liquid state and circulated, in particular, within the first supply circuit 2. By drawing in the gas in its liquid state, the first pumping device 9 also allows its pressure to be increased to a value between 6 and 17 bar.

[0056] The gas in liquid state, in a direction of circulation from the tank 8 to the high-pressure gas-consuming device 4, passes through a first heat exchanger 6, is pumped by a second pumping device 10 and passes through a second heat exchanger 7. Details concerning the two heat exchangers 6, 7 will be described later.

[0057] Following passage through the second heat exchanger 7, the gas flows to a high-pressure evaporator 11. The high-pressure evaporator 11 modifies the state of the gas circulating in the first supply circuit 2, changing it to a vapor or supercritical state. This state allows the gas to be compatible for supplying the high-pressure gas-consuming device 4. The evaporation of the gas into a liquid state can, for example, be achieved by heat exchange with a heat transfer fluid at a sufficiently high temperature to evaporate the gas into a liquid state, in this case glycol water, seawater, or steam.

[0058] The increase in gas pressure is ensured by the second pumping device 10 when it pumps the gas in its liquid state. The second pumping device 10 makes it possible to raise the pressure of the gas in its liquid state to a value between 30 and 70 bar for use with liquefied petroleum gas, and preferably between 150 and 400 bar for use with ethane, ethylene, or liquefied natural gas consisting mainly of methane.

[0059] Thanks to the combination of the second pumping device 10 and the high-pressure evaporator 11, the gas is at a pressure and in a state compatible for supplying the high-pressure consumer device 4. Such a configuration makes it possible to avoid the installation of high-pressure compressors on the first supply circuit 2 which present cost constraints and generate strong vibrations.

[0060] Within tank 8, some of the gas cargo may naturally vaporize and diffuse into a tank headspace 12. To prevent overpressure within tank 8, the gas in vapor form contained in the tank headspace 12 must be vented. However, the first supply circuit 2 is configured to use the gas in the vapor state liquid to supply the high-pressure gas-consuming device 4.

[0061] The supply system 1 therefore includes a second gas supply circuit 3, which uses the gas in the vapor state to supply the low-pressure gas-consuming device 5. The second supply circuit 3 thus extends between the tank head 12 and the low-pressure gas-consuming device 5. In order to draw the gas in the vapor state contained in the tank head 12, the second supply circuit 3 includes a compression device 13. In addition to drawing the gas in the vapor state, the compression device 13 also makes it possible to increase the pressure of the gas in the vapor state circulating in the second supply circuit 3 to a pressure between 6 and 20 bar absolute, so that the gas in the vapor state is at a pressure compatible for supplying the low-pressure gas-consuming device 5.The second supply circuit 3 thus makes it possible to supply the low-pressure gas-consuming device 5, while regulating the pressure within the tank 8 by drawing in the gas in vapor state present in the tank head 12. .

[0062] The presence of an excessive amount of gas in vapor form within the tank head 12 causes overpressure within the tank 8. It is therefore necessary to evacuate the gas in vapor form in order to lower the pressure within the tank 8. The excess gas in vapor form can then, for example, be removed by a burner 18. However, the supply system 1 according to the invention includes a return line 14 connected to the second supply circuit 3 downstream of the compression device 13 with respect to a direction of flow of the gas in vapor form circulating in the second supply circuit 3. Depending on the direction of flow of the gas in vapor form circulating in the return line 14, said gas passes first through the second heat exchanger 7, then through the first heat exchanger 6.The heat exchange taking place within the first heat exchanger 6 and the second heat exchanger 7 is therefore between the gas in the liquid state circulating in the first supply circuit 2 and the gas in the vapor state circulating in the return line 14. The objective of this heat exchange is to reliquefy the gas in the vapor state of the return line 14, so that it changes to the liquid state, and then return it to the tank 8 once this has been done.

[0063] The compression device 13 may be an oil compressor. The oil cools the compression device 13 while lubricating the moving parts of the compressor to limit wear on said moving parts and contributing to noise dissipation, making the oil compressor a preferred means for compressing gas in the vapor state. This type of compression device 13 includes a plurality of filters preventing oil from escaping from the compression device 13. However, such filtration is not perfect, and traces of oil may escape from the compression device 13, carried by the gas flow. in a vapor state.

[0064] Traces of oil can then circulate in the return line 14 to the second heat exchanger 7. The heat exchanges occurring within the first heat exchanger 6 and the second heat exchanger 7 result in the cooling of the gas in the vapor state circulating in the return line 14. The traces of oil also circulating in the return line 14 are therefore also cooled. However, the oil has phase change threshold temperatures significantly higher than those of the gas contained in the tank 8 and circulating in the feed system 1. The very high cooling capacities of the heat exchangers 6 and 7 therefore lead to the solidification of the traces of oil and their aggregation within said heat exchangers 6 and 7.Since the second heat exchanger 7 is the first through which the oil flows in the return line 14, the probability of oil solidification and aggregation is highest within it. However, such a phenomenon can also occur at the first heat exchanger 6.

[0065] Although the amount of oil exiting the compression device 13 is minimal, the accumulation of oil escaping from the compression device 13 and solidifying within one or the other of the heat exchangers 6, 7 over time eventually becomes problematic, leading to blockages within the heat exchangers 6, 7, cooling failures, and significant pressure drops in the vapor gas circulating in the return line 14, which is intended to be reliquefied. Replacing the compression device 13 with an oil-free compressor is possible but cumbersome and costly.

[0066] To circumvent such a problem without having to replace the compression device 13, the supply system 1 is equipped with a recirculation branch 15 starting at a divergence point 19 located on the return line 14 downstream of the second heat exchanger 7 and extending to the second supply circuit 3 upstream of the compression device 13. The recirculation branch 15 makes it possible to form a loop between the second supply circuit 3 and the return line 14.

[0067] Thanks to the recirculation branch 15, it is possible to circulate the gas in a closed loop through the heat exchangers 6, 7. The objective is to gradually increase the temperature within the heat exchangers 6, 7 so that the oil aggregates that have accumulated there melt and return to a liquid state, then are discharged from the heat exchangers 6, 7 carried by the flow of gas in a vapor state. The molten oil then flows through the return line 14, then through the recirculation branch 15 to reach the second supply circuit 3. The oil then enters the compression device 13 and is filtered there.

[0068] According to the first embodiment, the gas in the vapor state circulates within the heat exchangers 6, 7 in a semi-closed loop, that is to say, while circulating within the return line 14 and the heat exchangers 6, 7, the gas in the vapor state is always evacuated from the tank ceiling 12 and the low pressure gas consuming device 5 is always supplied with gas in a common manner.

[0069] To ensure a temperature rise within the heat exchangers 6, 7 and thus remove the oil that has accumulated there, the circulation of gas in the liquid state in the first supply circuit 2 must be stopped within the heat exchangers 6, 7. This must not, however, cause an interruption in the supply to the high-pressure gas-consuming device 4. The supply system 1 therefore includes a first bypass branch 16 and a second bypass branch 17, each extending in parallel respectively from the first heat exchanger 6 and the second heat exchanger 7, thus allowing the circulation of gas in the liquid state to be diverted so that it does not pass through the heat exchangers 6, 7, but while continuing to supply the high-pressure gas-consuming device 4.Since there is no longer any circulation of gas in liquid state, which comes from tank 8 and therefore has a very low temperature, within the heat exchangers 6, 7, these can heat up via the gas in vapor state which circulates in a loop within them.

[0070] Each bypass branch 16, 17 is connected on either side of one of the heat exchangers 6, 7. Thus, the gas in the liquid state circulating in the first supply circuit 2, although bypassing the heat exchangers 6, 7, is still pressurized by the second pumping device 10 to have a pressure compatible with the needs of the high-pressure gas-consuming device 4. The gas in the liquid state circulating in the first supply circuit 2 is also evaporated by the high-pressure evaporator 11. The configuration of the latter must, however, be modified, particularly with regard to its energy input, because since the gas in the liquid state has not been preheated by passing through the heat exchangers 6, 7, its evaporation therefore requires more energy.

[0071] Thus, the supply system 1 according to the invention is capable of implementing a management process enabling the supply system 1 to operate according to a first configuration, operated predominantly, during which the gas-consuming devices 4, 5 are supplied and the excess gas in vapor form is reliquefied before being returned to the tank, and according to a second configuration, operated occasionally, the purpose of which is to eliminate the oil aggregates that have accumulated within the heat exchangers 6, 7.

[0072] In order to control the gas flow within the supply system 1 according to the configuration to be applied, the supply system 1 includes a a recirculation valve 20 located on the recirculation branch 15 and a return valve 21 located on the return line 14 between the divergence point 19 and the tank 8. The recirculation valve 20 allows or prevents the flow of gas to the second supply circuit 3 while the return valve 21 allows or prevents the flow of gas to the tank 8. It is thus understood that, depending on the configuration implemented of the supply system 1, one of these valves is open while the other is closed.

[0073] Advantageously, the recirculation valve 20 also allows the expansion of the gas circulating in the recirculation branch 15. This expansion allows, downstream of the recirculation branch 15, a mixing of the gas coming from the return line 14, and therefore previously compressed by the compression device 13, and the gas coming directly out of the tank 8 at an equivalent pressure level.

[0074] The supply system 1 also includes a bypass valve 22, as well as a control valve 23 and a regulating valve 24. The bypass valve 22 is located on the first bypass branch 16, while the control valve 23 and the regulating valve 24 are located on a first portion 25 of the first supply circuit 2, which corresponds to the portion arranged in parallel with the first bypass branch 16 and which therefore passes through the first heat exchanger 6.

[0075] It is thus understood that access to the first bypass branch 16 is controlled by the bypass valve 22. Access to the first section 25 is controlled by the control valve 23 and the regulating valve 24. Advantageously, the control valve 23 and the regulating valve 24 are arranged on the first section 25 on either side of the first heat exchanger 6, the control valve 23 being upstream of the first heat exchanger 6 while the regulating valve 24 being downstream of the first heat exchanger 6. The presence of two valves makes it possible to completely isolate the first heat exchanger 6 from the rest of the first supply circuit 2.Although the control valve 23 alone is sufficient to prevent the circulation of gas in the liquid state in the first heat exchanger 6, it is advantageous to also implement the regulating valve 24 in order to avoid creating a pressure differential which could lead to evaporation of the gas in the liquid state.

[0076] The supply system 1 also includes a bypass element 26 arranged on the second bypass branch 17, as well as a control element 27 and a regulating element 28 arranged on a second portion 29 of the first supply circuit 2 which is arranged in parallel with the second bypass branch 17. The control element 27 and the regulating element 28 are arranged on either side of the second heat exchanger 7, the control element 27 being in upstream of the second heat exchanger 7, while the regulating element 28 is downstream of the second heat exchanger 7. The bypass element 26, the control element 27 and the regulating element 28 are respectively the counterparts of the bypass valve 22, the control valve 23 and the regulating valve 24, but interacting at the level of the second heat exchanger 7. The operation of the aforementioned elements with respect to the aforementioned valves is therefore the same.

[0077] In order to detect whether it is necessary to implement the second configuration of the supply system 1 to eliminate the oil present within the heat exchangers 6, 7, the supply system 1 includes a first measuring element 31, a second measuring element 32, a first measuring device 33 and a second measuring device 34.

[0078] The first measuring element 31 is configured to measure the pressure of the gas in the vapor state circulating in the return line 14 at the inlet of the first heat exchanger 6 and / or at the inlet of the second heat exchanger 7, while the second measuring element 32 is configured to measure the pressure of the gas in the vapor state circulating in the return line 14 at the outlet of the first heat exchanger 6 and / or at the outlet of the second heat exchanger 7. From these pressure measurements, a pressure differential can be deduced.A pressure differential always exists between the gas at the inlet and outlet of a heat exchanger 6, 7. However, if the pressure differential at the inlet and outlet of one of the heat exchangers 6, 7 is significant—for example, from 40 mbar for the first heat exchanger or from 200 mbar for the second—this means that the gas undergoes a significant pressure drop as it passes through said heat exchanger 6, 7. This is potentially due to an accumulation of oil aggregates within it. The second configuration of the supply system 1 can therefore be implemented following a pressure measurement by the measuring devices 31, 32. The second configuration can also be implemented after measuring a calculated pressure differential over time at at least one of the heat exchangers 6, 7.As an example, a pressure differential variation of more than 150%, preferably more than 100% compared to the pressure differential when the heat exchangers do not have oil aggregates, is considered the point at which the removal of accumulated oil is necessary.

[0079] The first measuring device 33 and the second measuring device 34 are configured to measure a gas temperature. More specifically, the first measuring device 33 is configured to measure the temperature of the gas in the liquid state circulating in the first supply circuit 2 at the inlet of the first heat exchanger 6 and / or at the inlet of the second heat exchanger 7. The second measuring device 34 is configured to measure the temperature gas circulating in the return line 14 at the outlet of the first heat exchanger 6 and / or at the outlet of the second heat exchanger 7.

[0080] A temperature differential between the temperature measured by the first measuring device 33 and the temperature measured by the second measuring device 34 is then calculated on the same heat exchanger. In other words, the temperature differential is calculated between the temperature of the gas in the liquid state circulating in the first supply circuit 2 at the inlet of the first heat exchanger 6, or of 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 of the second heat exchanger 7 respectively.If there is a significant temperature difference between the gas flowing in the first supply circuit 2 at the inlet of one of the heat exchangers 6, 7 and the gas flowing in the return line 14 at the outlet of the same heat exchanger 6, 7, this means that the heat treatment efficiency of said heat exchanger 6, 7 is abnormally reduced, and this may be due to the presence of oil aggregates within the heat exchanger 6, 7 in question. The temperature difference at which it is considered necessary to implement the second configuration can be on the order of 10°C, preferably 5°C. The second configuration can also be implemented after measuring the evolution of the temperature difference calculated over time at at least one of the heat exchangers 6, 7.

[0081] The supply system 1 can therefore be implemented according to the second configuration depending on the pressure differential or the temperature differential deduced from the various measurements described above. Both differentials can be calculated in order to limit potential measurement errors. It should also be noted, as illustrated in Figures 1 to 3, that the second measuring element 32 and the second measuring device 34 can be combined into a single unit.

[0082] Figure 2 represents the gas flow within the supply system 1 when the latter is implemented according to the first configuration. In Figures 2 and 3, solid lines symbolize gas flow while dashed lines symbolize the absence of gas flow.

[0083] As previously mentioned, the first configuration consists of supplying the gas-consuming devices 4, 5 while reliquefying the excess gas in vapor form before returning it to the tank 8. In this first configuration, the return valve 21, the control valve 23, the regulating valve 24, the control member 27 and the regulating member 28 are open, while the recirculation valve 20, the bypass valve 22 and the bypass member 26 are closed.

[0084] According to this first configuration, the gas in the liquid state contained in the tank 8 is pumped by the first pumping device 9 and circulates within the first supply circuit 2. The gas in liquid state passes through the first heat exchanger 6, is pumped and raised to a pressure compatible with the high-pressure gas-consuming device 4 by the second pumping device 10, passes through the second heat exchanger 7 and is evaporated by the high-pressure evaporator 11 before supplying the high-pressure-consuming device 4.

[0085] During the passage through the heat exchangers 6, 7, the gas in the liquid state undergoes a temperature increase due to the heat exchange carried out with the gas in the vapor state circulating in the return line 14, which facilitates its subsequent evaporation.

[0086] The gas in vapor form present in the tank head 12 is drawn into the second supply circuit 3, compressed by the compression device 13, and supplies the low-pressure gas-consuming device 5. The excess gas in vapor form, i.e., a surplus of gas in vapor form relative to the supply requirement of the low-pressure gas-consuming device 5, flows in the return line 14 and passes through the second heat exchanger 7 and then the first heat exchanger 6. The gas in vapor form is pre-cooled in the second heat exchanger 7 and is finally reliquefied in the first heat exchanger 6. Subsequently, the reliquefied gas returns to the tank 8.

[0087] As previously stated, after compression by the compression device 13, traces of oil exit the compression device 13, carried along by the gas in its vapor state. If these traces of oil circulate within the return line 14, their passage through one or the other of the heat exchangers 6, 7 cools them and may solidify them within said heat exchangers 6, 7.

[0088] Figure 3 represents the gas flow within the supply system 1 when the latter is implemented according to the second configuration. As previously stated, this second configuration is implemented following an accumulation of oil aggregates within one or the other of the heat exchangers 6, 7, and these aggregates must be removed to maintain the proper functioning of the supply system 1. Such an accumulation can be detected by the first measuring element 31 and the second measuring element 32 and / or by the first measuring device 33 and the second measuring device 34.

[0089] In this second configuration, the return valve 21, the control valve 23, the regulating valve 24, the control member 27 and the regulating member 28 are closed, while the recirculation valve 20, the bypass valve 22 and the bypass member 26 are open.

[0090] The objective being to increase the temperature within the heat exchangers 6, 7, there is no question of circulating the gas in a liquid state within them. However, the power supply for the high-pressure gas-consuming appliance 4 must be continued.

[0091] Thus, the gas in the liquid state contained in the tank 8 is pumped by the first pumping device 9 and circulates within the first supply circuit 2. The gas in the liquid state bypasses the first heat exchanger 6 by circulating in the first bypass branch 16, is pumped and raised to a pressure compatible with the high-pressure gas-consuming device 4 by the second pumping device 10, also bypasses the second heat exchanger 7 by circulating in the second bypass branch 17 and is evaporated by the high-pressure evaporator 11 before supplying the high-pressure-consuming device 4. Even though the gas in the liquid state is not cooled due to its bypassing of the heat exchangers 6, 7, the high-pressure evaporator 11 is capable of evaporating said gas in the liquid state.

[0092] The gas in vapor form is drawn from the tank head 12 by the compression device 13 and flows into the second supply circuit 3. When implemented according to the second configuration, the low-pressure gas-consuming device 5 must also be supplied. As mentioned previously, the first embodiment of the supply system 1 implements the second configuration in a semi-closed loop. A portion of the gas in vapor form can therefore supply the low-pressure gas-consuming device 5 if necessary; that is, the gas exiting the compression device 13 is simultaneously distributed to the low-pressure gas-consuming device 5 and into the return line 14.

[0093] The gas in its vapor state also flows in the return line 14 and passes through the second heat exchanger 7 and then the first heat exchanger 6. Since the gas in its liquid state does not flow through the heat exchangers 6 and 7, the gas in its vapor state is not reliquefied, and this leads to an increase in temperature within the heat exchangers 6 and 7. At the outlet of the first heat exchanger 6, the gas in its vapor state does not return to the tank 8 but flows through the recirculation branch 15 to be compressed again by the compression device 13 and recirculated in the return line 14 to pass through the heat exchangers 6 and 7 once more. The looped circulation of the gas in its vapor state through the heat exchangers 6 and 7 increases the temperature within them. The oil aggregates then fuse and the oil is eventually removed from the heat exchangers 6, 7 carried by the gas in its vapor state.The oil then also joins the compression device 13 via the recirculation branch 15 and is then retained by the filtration means of said compression device 13.

[0094] The second operating mode is implemented until the oil is completely removed from the heat exchangers 6, 7. A pressure differential measurement is taken by the first measuring element 31 and by the second measuring element 32 at the level of Each heat exchanger 6, 7 allows for the determination of whether the oil has been drained. Once this is done, the supply system 1 can again operate according to the first configuration. During the implementation of the second configuration, the low-pressure gas-consuming device 5 can still be supplied with vapor gas circulating in the second supply circuit 3. Access to the tank 8 for drawing vapor gas from the tank head 12 is also open during the implementation of the second configuration.

[0095] Figure 4 is a representation of a second embodiment of the feed system 1 according to the invention. The second embodiment differs from the first embodiment in that, when the second configuration is implemented, the gas in the vapor state circulates within the heat exchangers 6, 7 in a completely closed loop.

[0096] Since the supply of the low-pressure gas-consuming device 5 must however be maintained, the second embodiment of the supply system 1 includes an auxiliary supply branch 35 which provides a fluid connection between the tank 8 and the low-pressure gas-consuming device 5, in order to be able to supply the latter despite the closed loop implemented via the second supply circuit 3, the return line 14 and the recirculation branch 15.

[0097] The auxiliary supply branch 35 includes a compression member 36 capable of drawing in the gas in vapor state present in the tank head 12 and raising it to a pressure compatible with the needs of the low-pressure gas-consuming device 5. Thus, when the gas in vapor state circulates in the closed loop after being put into circulation by the compression device 13, it is the compression member 36 that draws in the gas in vapor state contained in the tank head 12 in order to supply the low-pressure gas-consuming device 5.

[0098] Furthermore, as illustrated in [Fig. 4], the supply system 1 includes a first auxiliary valve 37 located on the 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 located on the second supply circuit 3 between the connection of the return line 14 and the outlet of the auxiliary supply branch 35.

[0099] The first auxiliary valve 37 and the second auxiliary valve 38 completely isolate the closed loop, comprising part of the second supply circuit, the return line 14 and the recirculation branch 15, from the supply to the low-pressure gas-consuming device 5, which is provided in particular by the auxiliary supply branch 35. This configuration prevents any unwanted thermal phenomena between the gas flow from the return line 14 and comprising molten oil and gas coming directly from the tank ceiling 12 which has a much lower temperature, for example oil freezing in contact with low temperature vapor gas coming from the tank ceiling 12.

[0100] The remaining structural and functional characteristics of the second embodiment being identical to those of the first embodiment, reference will be made to the descriptions of figures 1 to 3 for the elements common to both embodiments.

[0101] 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.

[0102] The invention, as described above, achieves its intended purpose and provides a gas supply system for two gas-consuming devices, enabling the reliquefaction of excess gas in vapor form and also the removal of oil accumulated in the heat exchangers of said supply system. 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

Demands

1. Gas supply system (1) for at least one high-pressure gas-consuming appliance (4) and at least one low-pressure gas-consuming appliance (5) of a floating structure comprising at least one tank (8) configured to contain the gas, the supply system (1) comprising: - at least one first gas supply circuit (2) for the high-pressure gas-consuming appliance (4), comprising at least one first pumping device (9) configured to pump the gas taken from the liquid state in the tank (8), - at least one high-pressure evaporator (11) configured to evaporate the gas circulating in the first supply circuit (2), - at least one second gas supply circuit (3) for the low-pressure gas-consuming appliance (5), comprising at least one compression device (13) configured to compress gas taken from the vapor state in the tank (8) to a pressure compatible with the requirements of the low-pressure gas-consuming appliance (5), - 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) comprising at least one first heat exchanger (6) and at least one second heat exchanger (7), each configured to perform heat exchange between the gas in vapor state flowing in the return line (14) and the gas in liquid state flowing in the first supply circuit (2), the first supply circuit (2) comprising a second pumping device (10) interposed between the first heat exchanger (6) and the second heat exchanger (7), characterized in that the supply system (1) comprises a recirculation branch (15) connected at the inlet to a divergence point (19) disposed on the return line (14) between the first heat exchanger (6) and tank (8), the recirculation branch (15) comprising an outlet connected to the second supply circuit (3) between the tank (8) and the compression device (13), the first supply circuit (2) comprising a first bypass branch (16) arranged in parallel with a first portion (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 portion (29) of the first supply circuit (2) passing through the second heat exchanger (7).

2. Feeding system (2) 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 divergence point (16) and the tank (8).

3. Supply system (1) 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 portion (25) of the first supply circuit (2).

4. Supply system (1) according to claim 3, wherein the control valve (23) is disposed on the first portion (25) upstream of the first heat exchanger (6), the supply system (1) comprising a regulating valve (24) disposed on the first portion (25) downstream of the first heat exchanger (6).

5. Power supply system (1) 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 portion (29) of the first power supply circuit (2).

6. Feeding system (1) according to claim 5, wherein the control member (27) is disposed on the second portion (29) upstream of the second heat exchanger (7), the feeding system (1) comprising a regulating member (28) disposed on the second portion (29) downstream of the second heat exchanger (7).

7. Feeding system (1) according to any one of claims 1 to 6, comprising a first measuring element (31) and a second measuring element (32) configured to respectively measure a pressure of the gas flowing in the return line (14) at the inlet and outlet of the first heat exchanger (6) and / or at the inlet and outlet of the second heat exchanger (7).

8. Feeding system (1) according to any one of claims 1 to 7, comprising a first measuring device (33) and a second measuring device (34) configured to respectively measure a temperature of the gas flowing in the first feed circuit (2) at the inlet of the first heat exchanger (6) and of the gas flowing in the return line (14) at the outlet of the first heat exchanger (6) and / or of the gas flowing in the first feed circuit (2) at the inlet of the second heat exchanger (7) and of the gas flowing in the return line (14) at the outlet of the second heat exchanger (7).

9. Supply system (1) according to any one of claims 1 to 8, comprising an auxiliary supply branch (35) connected inlet to the second supply circuit (3) between the tank (8) and the outlet of the recirculation branch (15), the auxiliary supply branch (35) comprising an outlet connected to the second supply circuit (3) between the connection to the return line (14) and the low pressure gas consuming device (5), the auxiliary supply branch (35) comprising a compression member (36).

10. Supply system (1) according to claim 9, wherein the second supply circuit (3) comprises a first auxiliary valve (37) disposed between the inlet of the auxiliary supply branch (35) and the outlet of the recirculation branch (15) and a second auxiliary valve (38) disposed between the connection to the return line (14) and the outlet of the auxiliary supply branch (35).

11. A supply system (1) according to any one of claims 1 to 10, wherein the first pumping device (9) is configured to raise the pressure of the gas in the liquid state to a value between 6 and 17 bar and the second pumping device (10) is configured to raise the pressure of the gas in the liquid state to a value between 30 and 400 bar.

12. Supply system (1) according to any one of claims 1 to 11, wherein the compression device (13) is configured to raise a gas pressure to a value between 6 and 20 bar absolute.

13. Floating structure for the storage and / or transport of gas in liquid form, comprising at least one tank (8) of gas in liquid form, at least one high-pressure gas-consuming device (4), at least one low-pressure gas-consuming device (5) and at least one gas supply system (1) for these devices according to any one of claims 1 to 12.

14. A gas management method implemented by a feed system (1) according to any one of claims 1 to 12, wherein: - the gas is circulated in liquid form in the first supply circuit (2) within the first heat exchanger (6) and the second heat exchanger (7) and the gas is circulated in vapor form within the return line (14) to the tank (8) according to a first configuration, - the gas is circulated in the liquid state in the first supply circuit (2) within the first bypass branch (16) and the second bypass branch (17) and the gas is circulated in the vapor state within the recirculation branch (15) according to a second configuration.

15. Management method according to claim 14, implemented by a supply system (1) according to claims 2, 4 and 6, wherein the return valve (21), the control valve (23), the regulating valve (24), the control member (27) and the regulating member (28) are open while the recirculation valve (20), the bypass valve (22) and the bypass member (26) are closed when the first configuration is active, the return valve (21), the control valve (23), the regulating valve (24), the control member (27) and the regulating member (28) being closed while the recirculation valve (20), the bypass valve (22) and the bypass member (26) being open when the second configuration is active.

16. Management method according to claim 14 or 15, implemented by a feed system (1) according to claim 7, wherein a selection between the first configuration and the second configuration is dependent on a pressure difference between the pressure measured by the first measuring element (31) and the pressure measured by the second measuring element (32) of the gas flowing in the return line (14) at the inlet and outlet of the first heat exchanger (6) and / or at the inlet and outlet of the second heat exchanger (7).

17. A management method according to any one of claims 14 to 16, implemented by a feed system (1) according to claim 8, wherein a selection between the first configuration and the second configuration is dependent on a temperature difference between the temperature measured by the first measuring device (33) and the temperature measured by the second measuring device (34) respectively of the gas flowing in the first feed circuit (2) at the inlet of the first heat exchanger (6) and of the gas flowing in the return line (14) at the outlet of the first heat exchanger (6) and / or of the gas flowing in the first feed circuit (2) at the inlet of the second heat exchanger (7) and of the gas flowing in the return line (14) at the outlet of the second heat exchanger (7).

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