System for managing gas contained within a floating structure

Abstract

The present invention relates to a system (1) for managing a gas contained in a tank (2), the system (1) comprising: - at least one supply circuit (6); - at least one heat treatment circuit (8); - at least one first heat exchanger (13); - at least one cooling circuit (17); and - at least one second heat exchanger (16). In the system (1), the heat treatment circuit (8) comprises at least one first branch (9) connected to a first compression stage (11) of a compression device (7) and a second branch (10) connected to a second compression stage (12) of the compression device (7), and the first branch (9) and the second branch (10) merge at a merging point (14) in the heat treatment circuit (8).

Description

Technical Field

[0001] The present invention relates to the field of floating structures for storing and / or transporting gases in a liquid state, and more particularly to a system for managing gases stored and / or transported inside such vessels.

Background Art

[0002] During navigation carried out by a floating structure equipped with a tank for a gas in a liquid state intended for consumption and / or delivery to a destination, the floating structure uses the gas evaporated inside the tank, and in this case, the gas may tend to be compressed and supplied to the engine of the floating structure.

[0003] Furthermore, in cases where the gas evaporated inside the tank is excessive, it is known to circulate the gas that did not function to supply the engine of the floating structure through one or more heat exchangers and then reliquefy the gas by sending it back into the tank.

[0004] However, sometimes a given floating structure, and more particularly the tank included in such a floating structure, may be capable of storing and / or transporting different types of gases in a liquid state. This may cause the floating structure to contain, for example, a load of liquefied natural gas composed almost exclusively of methane or a load of ethane that may actually contain a small proportion of methane.

[0005] The different types of gases exhibit different chemical structures. Due to the differences in the structures, different characteristics, such as the evaporation temperature or the compatibility with at least one device incorporated in the floating structure and suitable for consuming the gas, such as an engine, distinguish one gas from another.

[0006] As a result, depending on various different parameters of the gas, using the gas in the tank as fuel or reliquefying the gas according to the properties of the gas becomes complicated because there are certain possibilities that are not optimal for the system to be used, thereby reducing the efficiency of gas reliquefaction.

Summary of the Invention

Means for Solving the Problems

[0007] The present invention is a system for enabling adaptation to heterogeneous gases to be stored and / or transported, and thus for managing the gas contained in at least one tank of a floating structure provided with at least one gas consumption device, - at least one gas supply circuit of the gas consumption device, the supply circuit comprising at least one compression device, the compression device comprising at least two compression stages and being configured to compress the gas taken in from the tank in vapor state to a pressure adapted to the requirements of the gas consumption device; a supply circuit, - at least one heat treatment circuit for the gas in vapor state compressed by at least one compression stage of the compression device; - at least a first heat exchanger configured to effect heat exchange between the gas in vapor state circulating between the tank and the compression device in the supply circuit and the gas in vapor state circulating in the heat treatment circuit; - at least one cooling circuit comprising at least one pump configured to take in the gas in liquid state in the tank; - at least a second heat exchanger configured to effect heat exchange between the gas in vapor state circulating downstream of the first heat exchanger in the heat treatment circuit and the gas circulating in the cooling circuit in a system for managing, The heat treatment circuit comprises at least a first branch connected to the first compression stage of the compression device and a second branch connected to the second compression stage of the compression device, the second compression stage being arranged downstream of the first compression stage, and the first branch and the second branch merging with each other at the confluence point of the heat treatment circuit, and a system is proposed.

[0008] With such a management system, the gaseous gas stored in the tank can be optimally consumed or liquefied regardless of its properties. Depending on the characteristics of the gas to be stored and / or transported, and also depending on the compatibility of the gas with the gas consumption device, the management system can be adapted to be systematically and efficiently gas-treated. The compression stages described in the present invention may correspond to a plurality of compressors.

[0009] The supply circuit functions to take in the gaseous gas generated in the headspace of the tank. This gaseous gas is due to the evaporation of a part of the content of the liquid gas stored in the tank. Such evaporation may occur naturally or may be forced by some devices incorporated in the floating structure. Therefore, although the gaseous gas can be consumed or reliquefied, the gaseous gas generally has to be discharged to adjust the pressure in the tank.

[0010] Accordingly, the compression device provides for the intake of the gas in vapor state and compresses the same. The compression device may be, for example, a plurality of compressors arranged in series with each other, or a single compressor having a plurality of compression stages. The greater the number of compression stages through which the gas in vapor state passes, the higher the pressure applied to the gas in vapor state. The gas compressed by the entire compression device may reach a pressure included in the range of 250 to 400 bar. The pressure applied to the gas in vapor state is important for supplying the gas-consuming device. This is because this gas-consuming device can consume the gas in vapor state only when the gas is at a suitable pressure. Further, the gas-consuming device does not necessarily tend to consume the gas stored in the tank depending on the chemical structure of the gas.

[0011] In this case, in such a configuration, the gas in vapor state is not discharged from the tank for supply purposes.

[0012] When the gas in vapor state does not match the gas-consuming device or the supply to the gas-consuming device is unnecessary, the gas in vapor state circulates within the heat treatment circuit. Even when the gas-consuming device only requires a vapor-state gas of a required supply fraction, the remaining gas in vapor state circulates within the heat treatment circuit. One of the functions of this heat treatment circuit is to participate in the reliquefaction of the compressed gas in vapor state.

[0013] The first heat exchanger functions to precool the compressed gas in vapor state and heat the gas in vapor state at the outlet side of the tank. By precooling the compressed gas, subsequent heat treatment, particularly its reliquefaction for example, becomes easier. Thereby, the first heat exchanger functions to improve the overall efficiency of the management system. This is because the low temperature of the gas in vapor state at the outlet side of the tank indirectly participates in the reliquefaction of the compressed gas in vapor state through the heat exchange occurring in the first heat exchanger.

[0014] The cooling circuit may have multiple functions, such as being involved in the re-liquefaction of the gaseous state gas circulating within the heat treatment circuit or being involved in the management of the tank pressure. For this purpose, the gaseous state gas in the liquid state within the tank is sucked in by a pump, and this pump is, for example, submerged on the bottom side of the tank and circulates the gaseous state gas in the liquid state inside the cooling circuit.

[0015] The gaseous state gas in the liquid state can flow through the second heat exchanger by circulating through the cooling circuit, and this second heat exchanger also allows the gaseous state gas circulating within the heat treatment circuit to flow through. As a result, the heat exchanger enables the re-liquefaction of the gaseous state gas without causing the evaporation of the gaseous state gas in the liquid state circulating through the cooling circuit. When the gaseous state gas is re-liquefied, the re-liquefied gas can return to the tank by circulating inside the cooling circuit, similar to the gaseous state gas in the liquid state used for re-liquefaction.

[0016] The advantage of the heat treatment system according to the present invention is that there are a plurality of branch paths on the outlet side of the compression device inside the heat treatment circuit. As a result, the gas can be systematically and optimally consumed and / or re-liquefied regardless of the nature of the gas contained in the tank. As an example, a gas that is intended to be consumed at a low pressure and is more efficiently re-liquefied at a low pressure can exit from the compression device at the first compression stage, while a gas that is intended to be consumed at a high pressure and is more efficiently re-liquefied at a high pressure can exit from the compression device at the second compression stage. The same applies to a gas that is intended to be consumed at a high pressure and is more efficiently re-liquefied at a low pressure or vice versa.

[0017] The connection to the first compression stage and the second compression stage means that the first branch path is connected to the outlet side of the first compression stage and the second branch path is connected to the outlet side of the second compression stage. In other words, the first compression stage is the final stage for compressing the gaseous state gas circulating within the first branch path, and the second compression stage is the final stage for compressing the gaseous state gas circulating within the second branch path.

[0018] The gas compressed to the first compression stage by the compression device has a pressure included in the range of 7 to 20 bar. The gas compressed to the second compression stage by the compression device has a pressure included in the range of 120 to 150 bar. In such a configuration, the gas can proceed through two different compression stages from the compression device. Thereafter, the two branch paths merge, whereby the compressed gas is processed inside the heat treatment circuit regardless of the pressure at which the gas was compressed.

[0019] As described above, the management system may be adapted to the nature and / or composition of the gas contained in the tank. Thereby, in the case where the floating structure and its tank are configured to transport and / or store a gas, for example methane or ethane, the management system enables the circulation of the gas in the first branch path and / or the second branch path when the gas contained in the tank is methane, and is configured to enable circulation only in the first branch path when the gas contained in the tank is ethane. Such a configuration functions to process each type of gas as well as possible from the viewpoints of supply and / or reliquefaction.

[0020] According to one feature of the present invention, the confluence point is arranged between the compression device and the first heat exchanger. It is particularly advantageous to precool the compressed gas regardless of the pressure at which the gas was compressed. Thereby, the confluence point is preferably positioned upstream of the first heat exchanger when viewed in the circulation direction of the compressed gas.

[0021] According to one feature of the present invention, the heat treatment circuit comprises at least one expansion member arranged downstream of the first heat exchanger. After being pre-cooled, the gaseous gas is expanded to reduce its pressure, whereby the gas is further cooled and even re-liquefied. The expansion may be carried out, for example, even in the case where the gas is ethane, the purpose of which is to extract the methane fraction contained in the ethane by maintaining the ethane in the gaseous state, while producing a two-phase mixture in order to re-liquefy the ethane. The expansion can help the formation of the two-phase mixture by changing the phase change point of the gas by reducing the pressure of the gas.

[0022] According to one feature of the present invention, the expansion member is arranged between the first heat exchanger and the second heat exchanger. Such a specific layout helps to prepare the gaseous gas for re-liquefaction, particularly by the second heat exchanger.

[0023] According to one feature of the present invention, the second branch of the heat treatment circuit comprises a control member. The second branch is connected to the second compression stage, i.e., the compression stage where the gas is most compressed. Thereby, the control member arranged in the second branch functions to control the flow rate of the gaseous gas in the second branch. When appropriate, in addition to providing flow rate adjustment, the control member can expand the gaseous gas circulating in the second branch. The expansion of the gas may advantageously be before the cooling of the gas inside the first heat exchanger so that the gas pressure is adapted to the technology of the first heat exchanger.

[0024] According to one feature of the present invention, the first branch does not have a control member. When the gas is only compressed up to the first compression stage, there is no need to expand the gas.

[0025] According to one feature of the present invention, the gas consumption device is a high-pressure gas consumption device, and the supply circuit is configured to supply the high-pressure gas consumption device and / or the low-pressure gas consumption device. In other words, there are at least two gas consumption devices capable of supplying the gaseous gas stored in the tank. As an example, the high-pressure gas consumption device may be an engine for propelling a floating structure, while the low-pressure gas consumption device may be a generator of the floating structure. Such two examples of gas consumption devices may or may not be compatible with the gas stored and / or transported in the tank, and in the case of compatibility, they may be compatible with a specific pressure range.

[0026] According to one feature of the present invention, the supply to the low-pressure gas consumption device by the supply circuit at least partially passes through the first branch path. As described above, the first branch path is connected to the first compression stage of the compression device, that is, the stage where the gas is compressed at a low pressure. Therefore, although the first compression stage is suitable for compressing the gaseous gas to a pressure suitable for the requirements of the low-pressure gas consumption device, this is only the case when the low-pressure gas consumption device can consume the type of gas stored in the tank. Therefore, for this reason, the supply to the low-pressure gas consumption device partially coincides with the first branch path.

[0027] According to one feature of the present invention, the heat treatment circuit includes a separation device having an inlet side disposed downstream of the second heat exchanger. This separation device functions to separate the gas phase of the gas from the liquid phase after the gas circulating in the heat treatment circuit crosses the second heat exchanger. The separation device may be used in the case where the gas circulating in the heat treatment circuit is partially reliquefied, whereby the fraction of the gas that has not been reliquefied can be retained.

[0028] According to one feature of the present invention, the separation device comprises a first outlet configured to allow a gas in a vapor state to exit from the separation device, and the heat treatment circuit comprises a third branch connecting the first outlet of the separation device to the supply circuit of the low-pressure gas consuming device. As described above, when the gas contained in the tank is ethane, the gas can be heat-treated to re-liquefy the ethane while maintaining methane, which is present in the ethane in a minimum proportion, in a vapor state. Thereafter, the methane can be circulated outside the separation device through the first outlet, in this case inside the third branch, and supplied to the low-pressure gas consuming device. This low-pressure gas consuming device has no tendency to consume ethane, and the only means of supplying a gas in a vapor state into the low-pressure gas consuming device is to isolate the methane contained in the ethane and provide said methane.

[0029] According to one feature of the present invention, the heat treatment circuit comprises a fourth branch connecting the first outlet of the separation device to the supply circuit at a point located between the tank and the first heat exchanger. This fourth branch is used, for example, in cases of partial re-liquefaction where isolation of the gas components is not intended. In this case, the gas remaining in a vapor state after crossing the second heat exchanger is separated inside the separation device and then circulates through the fourth branch, thereby recirculating inside the supply circuit and being consumed or new attempts at re-liquefaction are made.

[0030] According to one feature of the present invention, the separation device comprises a second outlet configured to allow a gas in a liquid state to exit from the separation device, and the heat treatment circuit comprises a fifth branch connecting the second outlet of the separation device to the cooling circuit. Thereby, the re-liquefied gas exits the separation device in a liquid state, circulates through the fifth branch, and merges into the cooling circuit to be returned into the tank.

[0031] According to one feature of the present invention, the heat treatment circuit comprises a sixth branch path connecting the outlet of the path from the second heat exchanger, which is a component of the heat treatment circuit, to the fifth branch path. In other words, this sixth branch path bypasses the separation device and directly merges into the cooling circuit via the fifth branch path. When it is certain that complete reliquefaction has occurred after the gas has traversed the second heat exchanger, it is advantageous to bypass the separation device in order to prevent unnecessary heat input.

[0032] According to one feature of the present invention, the management system comprises a third heat exchanger configured to effect heat exchange between the gas in liquid state circulating inside the cooling circuit and the refrigerant fluid circulating within the cooling loop. This third heat exchanger functions to subcool the gas in liquid state, thereby improving the reliquefaction of the gaseous state gas circulating through the second heat exchanger, for example, by circulating the subcooled gas in liquid state inside the second heat exchanger.

[0033] The subcooled gas in liquid state may be returned into the tank, thereby reducing the overall temperature of the tank and, consequently, the pressure of the tank. The fluid refrigerant circulating through the cooling loop used to subcool the gas in liquid state may be, for example, nitrogen.

[0034] According to one feature of the present invention, the management system comprises an additional branch path connecting the first compression stage of the compression device to the tank, and the management system further comprises a temperature exchanger configured to effect a heat exchanger between the gaseous state gas circulating within the additional branch path and the refrigerant fluid circulating through the reliquefaction loop. This is an alternative embodiment that may be implemented, for example, when the aforementioned third heat exchanger does not exist or to process a large amount of gaseous state gas.

[0035] The presence of an additional branch and a temperature exchanger may be useful, for example, in cases where the gaseous state gas circulating from the tank to the compression device is too little for efficient precooling. The temperature exchanger may also be used when the temperature of the gaseous state gas contained in the tank is too high to properly reliquefy the gaseous state gas circulating in the heat treatment circuit, and moreover, when the gaseous state gas cannot be subcooled.

[0036] In such a configuration, at least a part of the compressed gaseous state gas intended to be reliquefied may circulate in the additional branch and be separately reliquefied by a heat exchanger operated inside the temperature exchanger. Similar to the cooling loop described above, a refrigerant fluid, such as nitrogen, may flow through the reliquefaction loop.

[0037] The additional branch extends to the tank, whereby the gas can circulate in the liquid state to the tank when reliquefied inside the temperature exchanger.

[0038] According to a feature of the present invention, the cooling circuit includes at least one end component that opens into the tank, and this end component is an atomizer member and / or an orifice disposed in the lower part of the tank.

[0039] In addition to being involved in the reliquefaction of the gaseous state gas, the cooling circuit can also be involved in the management of the pressure of the tank and the overall temperature of the gas contained in the tank.

[0040] The management system may include a single end component that may be the orifice of the atomizer member, or may include two end components including the orifice and the atomizer member.

[0041] To participate in the cooling of the tank, the gas in the liquid state circulates within the cooling circuit, is subcooled by the third heat exchanger, and can then return to the tank via the orifice and / or the atomizer member. The orifice provides a return to the interior of the tank in order to lower the overall temperature of the gas in the liquid state within the tank. The atomizer member functions to spray the gas in the liquid state into the headspace of the tank, thereby promoting the condensation of the gas in the liquid state present in the headspace of the tank and reducing the pressure of the tank.

[0042] The present invention further encompasses a floating structure comprising at least the management system described above, and the tank contains liquefied natural gas.

[0043] According to a feature of the present invention, the floating structure comprises at least the management system described above, and the tank contains ethane.

[0044] As described above, the nature of the gas contained within the tank is adapted to determine the operation of the management system, the manner of supply to the gas-consuming device, and the manner of re-liquefaction of the vaporous gas.

[0045] The present invention further relates to a method for managing the gas contained within at least one tank of a floating structure, implemented by the management system described above, and during the management, - when the gas contained within the tank is liquefied natural gas, circulating the gas through the first branch and / or the second branch of the heat treatment circuit, or - when the gas contained within the tank is ethane, circulating the gas within the first branch of the heat treatment circuit and preventing the circulation of the gas within the second branch, covering the method.

[0046] Thereby, the management method functions to adapt the management system with respect to gas consumption or re-liquefaction, regardless of whether the gas contained within the tank is liquefied natural gas or ethane.

[0047] Another feature and advantage of the present invention should become apparent from the following description, on the one hand, and from a plurality of examples of embodiments shown in connection with the accompanying schematic diagrams, but not limited thereto.

Brief Description of the Drawings

[0048]

Figure 1

Figure 2

Figure 3

Figure 4

Mode for Carrying Out the Invention

[0049] FIG. 1 shows a management system 1 according to the present invention. This management system 1 may be incorporated inside a floating structure, for example, a ship for storing and / or transporting a gas in a liquid state contained in at least one tank 2. The gas in the liquid state may naturally and partially evaporate inside the head space 3 of the tank 2.

[0050] To manage the pressure of the tank 2 that increases due to the presence of gas in a vapor state inside the head space 3, the management system 1 can process the gas and thereby supply at least one gas-consuming device. In FIG. 1, the management system is configured to supply a high-pressure gas-consuming device 4 and a low-pressure gas-consuming device 5. The high-pressure gas-consuming device 4 may be, for example, an engine for propelling a floating structure. The low-pressure gas-consuming device 5 may be a generator that supplies electricity to the floating structure. The high-pressure gas-consuming device 4 and the low-pressure gas-consuming device 5 have their own unique conditions regarding the supply of gas, and the gas needs to have specific properties and a specific pressure so as to meet the requirements of each gas-consuming device 4, 5.

[0051] To provide supply to the gas-consuming devices 4, 5, the management system 1 includes a supply circuit 6 extending from the tank 2 to the high-pressure gas-consuming device 4. This supply circuit 6 includes a compression device 7 for sucking in the gas in a vapor state contained in the head space 3 of the tank 2 and compressing this gas to a pressure that meets the requirements of the high-pressure gas-consuming device 4.

[0052] In FIG. 1, the compression device 7 is schematically shown as a compressor in series, but the compression device 7 may be a single multi-stage compressor. Thereby, the compression device 7 has a plurality of compression stages for compressing the gas in a vapor state to a variable high pressure. The more compression stages the gas in a vapor state passes through, the higher the pressure of the compressed gas becomes. In this case, the gas in a vapor state can pass through all the compression stages of the compression device 7 and reach a pressure suitable for supply to the high-pressure gas-consuming device 4. The gas in a vapor state can reach a pressure value included in the range of 250 to 400 bar at the outlet side of the entire compression device 7.

[0053] The management system 1 further includes a heat treatment circuit 8. This heat treatment circuit 8 is connected to the supply circuit 6, more specifically, at the compression device 7. The particularity of the management system 1 according to the present invention is that the heat treatment circuit 8 includes a first branch path 9 connected to the first compression stage 11 and a second branch path 10 connected to the second compression stage 12 arranged downstream of the first compression stage 11, respectively. Thereby, the first branch path 9 and the second branch path 10 function to circulate the gaseous state gas at two different pressure levels inside the heat treatment circuit 8. Further, a part of the supply circuit 6 is connected to the first branch path 9, and this first branch path 9 is connected to the low-pressure gas consumption device 5. Such a connection is used because the gaseous state gas compressed at the first compression stage 11 has a pressure suitable for supply to the low-pressure gas consumption device 5. The gaseous state gas compressed up to the first compression stage 11 has a pressure included in 7 - 20 bar, while the gaseous state gas compressed up to the second compression stage 12 has a pressure included in 120 - 150 bar.

[0054] In addition to the connection to different compression stages, the first branch path 9 and the second branch path 10 are distinguished from each other by the fact that the second branch path 10 includes a control member 32, while the first branch path has no control member. The control member 32 functions to adjust the flow rate through the second branch path 10, but can also provide the expansion of the gas circulating through the second branch path 10 after the compression of the gas up to the second compression stage 12.

[0055] One of the purposes of the heat treatment circuit 8 is to participate in re-liquefying the gaseous state gas not used for supply to the gas consumption devices 4, 5 and limiting the losses related to the evaporation of the gas stored in the tank 2. For this purpose, the management system 1 includes a first heat exchanger 13 configured to perform a heat exchange between the compressed gaseous state gas circulating in the heat treatment circuit 8 and the gaseous state gas circulating upstream of the compression device 7 in the supply circuit 6.

[0056] As a result, the first heat exchanger 13 functions to pre-cool the gas in a vapor state circulating in the heat treatment circuit 8 by using the gas in a vapor state on the outlet side of the tank 2. In this case, the gas in a vapor state on the outlet side of the tank 2 is heated by taking in the calories of the gas in a vapor state circulating in the heat treatment circuit 8.

[0057] It should be noted that the first branch path 9 and the second branch path 10 merge at the confluence point 14. This confluence point 14 is preferably arranged upstream of the first heat exchanger 13, whereby all the gas in a vapor state circulating in the heat treatment circuit 8 is pre-cooled by flowing through the first heat exchanger 13. However, the management system 1 may be configured such that the first branch path 9 or the second branch path 10 bypasses the first heat exchanger 13 (not shown). In such a case, the confluence point 14 is arranged downstream of the first heat exchanger 13.

[0058] The pre-cooled gas in a vapor state is expanded by an expansion member 15 provided on the outlet side of the first heat exchanger 13. By expanding the gas in a vapor state, it becomes possible to further reduce its pressure and temperature. The expansion member 15 also changes the temperature of the state change of the gas in a vapor state. Thereafter, the gas in a vapor state flows across the second heat exchanger 16 with the intention of being at least partially re-liquefied. In FIG. 1, the expansion member 15 is arranged between the first heat exchanger 13 and the second heat exchanger 16, but the expansion member 15 may be arranged downstream of the second heat exchanger 16.

[0059] In order to perform efficient reliquefaction, the management system 1 includes a cooling circuit 17 that circulates the gas in a liquid state taken out from the tank 2 inside. This cooling circuit 17 preferably includes a pump 18 that is submerged on the bottom side of the tank 2 and circulates the gas in a liquid state inside the cooling circuit 17. Among the various different functions of the cooling circuit 17, one function is to be involved in the reliquefaction of the gas in a vapor state in the heat treatment circuit 8. The gas in a liquid state circulating in the cooling circuit 17 can flow across a second heat exchanger 16 that causes internal heat exchange with the gas in a vapor state circulating in the heat treatment circuit 8. In this case, the gas in a vapor state is reliquefied.

[0060] In order to improve the reliquefaction of the gas in a vapor state circulating in the second heat exchanger 16, the management system 1 includes a third heat exchanger 19 through which the gas in a liquid state circulating in the cooling circuit 17 can flow.

[0061] The third heat exchanger 19 functions to supercool the gas in a liquid state in order to compensate for the calories taken in by the gas in a liquid state during the heat exchange occurring inside the second heat exchanger 16. In order to supercool the gas in a liquid state, the third heat exchanger 19 is also traversed by a cooling loop 20 that circulates a refrigerant fluid for supercooling the gas in a liquid state inside. The refrigerant fluid circulating through this cooling loop 20 may be, for example, nitrogen.

[0062] When at least a part of the gas circulating in the heat treatment circuit 8 is reliquefied, this gas can circulate to a separation device 21 that includes an inlet side 22 where the gas at the outlet side of the second heat exchanger 16 flows in. This separation device 21 is used to separate the liquid fraction from the vapor fraction of this gas when the gas is not completely reliquefied. The separation device 21 includes a first outlet 23 that enables the vapor fraction to exit from the separation device 21 and a second outlet 24 that enables the liquid fraction to exit from the separation device 21.

[0063] When the vapor fraction is present within the separation device 21, it can proceed through the first outlet 23 and circulate within the third branch path 25 and the fourth branch path 26. The third branch path 25 is connected to the low-pressure gas consumption device 5, whereby the vapor fraction can be supplied to the low-pressure gas consumption device 5 when the gas under consideration may be consumed by the low-pressure gas consumption device 5. The fourth branch path is connected to the supply circuit 6, enabling the recirculation of the unliquefied gaseous state gas within the supply circuit 6, whereby the gas is consumed or reliquefied.

[0064] The liquid fraction present within the separation device 21 can proceed through the second outlet 24 and circulate within the fifth branch path 27 that connects the separation device 21 to the cooling circuit 17. In this case, the reliquefied gas circulates to the tank 2 after reaching the fifth branch path 27. In FIG. 1, the fifth branch path 27 is connected to the cooling circuit 17, but the fifth branch path 27 may also extend directly to the tank 2.

[0065] The heat treatment circuit 8 further includes a sixth branch path 28 that extends from the outlet side of the second heat exchanger 16 to the fifth branch path 27 on the upstream side of the separation device 21. By means of this sixth branch path 28, it becomes possible to directly return the reliquefied gas into the tank 2 by bypassing the separation device 21. Such a bypass functions to prevent unnecessary heat input due to the gas passing through the separation device 21. Therefore, the sixth branch path 28 is used when all the gaseous state gas circulating within the heat treatment circuit 8 is reliquefied by crossing the second heat exchanger 16.

[0066] After circulating through the cooling circuit 17 after being reliquefied within the heat treatment circuit 8, the gas in the liquid state is returned into the tank 2 via at least one end component 29. The end component 29 can enable the adjustment of the temperature of the gas contained within the tank 2 and / or the pressure of the tank 2. Thereby, the end component 29 may be an orifice 30 or a sprayer member 31. The orifice 30 may be disposed on the bottom side of the tank 2.

[0067] The above-described third heat exchanger 19 makes it possible to lower the temperature of the gas in the liquid state contained in the tank 2. As a result, the gas in the liquid state is taken in from the tank 2, supercooled by flowing through the third heat exchanger 19, and returned to the tank 2 through the orifice 30 while remaining supercooled. Thereby, the overall temperature of the gas in the liquid state contained in the tank 2 can be decreased over time.

[0068] The pressure of the tank 2 may be reduced in the case where the end part 29 or at least one end part 29 is the atomizer member 31. This atomizer member 31 sprays the gas in the liquid state in the head space 3 of the tank 2 to condense the gas in the vapor state existing in this head space 3, and thereby functions to reduce the pressure of the tank 2. Further, the atomizer member 31 can spray the gas in the liquid state pre-supercooled through the third heat exchanger 19 to promote the condensation of the gas in the vapor state in the head space 3 of the tank 2.

[0069] When the generation of the gas in the vapor state in the head space 3 of the tank 2 is not sufficient to satisfy the consumption in the high-pressure gas consuming device 4 and / or the low-pressure gas consuming device 5, the management system 1 may be configured to supply the gas in the liquid state to the low-pressure gas consuming device. Thereby, the management system may include an additional supply device 33. This additional supply device 33 may be connected to, for example, the cooling circuit 17, and thereby, assisted by the pump 18, it is possible to ensure circulation inside the additional supply circuit 33.

[0070] The additional supply circuit 33 is divided into a high-pressure passage 34 and a low-pressure passage 35, each intended to supply the high-pressure gas consuming device 4 and the low-pressure gas consuming device 5. The high-pressure passage 34 includes a high-pressure pump 36 and a high-pressure evaporator 37. The high-pressure pump 36 brings the gas in the liquid state to a pressure suitable for the high-pressure gas consuming device 4.

[0071] The high-pressure evaporator 37 functions to evaporate the liquid-state gas at high pressure, thereby changing the gas into a vapor state so that it can be consumed by the high-pressure gas consuming device 4.

[0072] The low-pressure passage 35 includes a low-pressure evaporator 38 which evaporates the liquid-state gas, so that when this gas is suitable for supply to the low-pressure gas consuming device 5, the low-pressure gas consuming device 5 can consume the gas. The low-pressure passage 35 does not include a pump like the high-pressure passage 34. This is because it is sufficient to circulate the liquid-state gas by the pump 18 in order to pressurize the liquid-state gas to a pressure compatible with the low-pressure gas consuming device 5.

[0073] The management system 1 may further include a discharge passage 39 connected to the supply passage 6 and extending to the burner 40. This discharge passage 39 functions to dispose of the vapor-state gas in the head space 3 of the tank 2 and prevent overpressure inside the tank 2, thereby preventing the vapor-state gas from being consumed or reliquefied.

[0074] To determine the internal paths and gas pressures of the management system 1, the management system 1 includes, in addition to the aforementioned expansion member 15 and control member 32, a plurality of expansion elements and valves. Thereby, the heat treatment circuit 8 includes a first adjustment element 41 provided upstream of the separation device 21 and a second adjustment element 42 arranged in the sixth branch path 28. The first adjustment element 41 and the second adjustment element 42 control the gas flow rate circulating inside the branch path of the part of the circuit under consideration, and also control the gas pressure, although not to the extent of this gas flow rate.

[0075] The valve may be in an open position or a closed position depending on the properties of the gas contained in the tank 2 and the mode of use of the gas, which will be described in detail later. Thereby, the first branch path 9 is provided with a first valve 43, and the second branch path 10 may be provided with a second valve 44 in addition to the control member 32 when the adjustment of the flow rate of the gaseous gas by this control member 32 is not possible. Further, the third branch path 25 is provided with a third valve 45, and the fourth branch path 26 is provided with a fourth valve 46.

[0076] Furthermore, the cooling circuit 17 is provided with a fifth valve 47 that functions to allow the liquid-state gas to flow through the second heat exchanger 16.

[0077] Finally, the portion of the supply circuit 6 that connects the first branch path 9 to the low-pressure gas consuming device 5 is provided with a sixth valve 51.

[0078] Figures 2 and 3 show examples of the gas circulation inside the management system 1 according to the properties of the gas. In Figure 2, the gas contained in the tank 2 is methane, while Figure 3 is an example of the circulation when the gas contained in the tank 2 is ethane. In each figure, the solid line corresponds to the line through which the gas circulates or can circulate, while the dashed line corresponds to the line through which the gas does not circulate.

[0079] Therefore, in Figure 2, the gas contained in the tank 2 and capable of circulating in the management system 1 is methane, more precisely, natural gas mainly formed from methane. Methane may be consumed by the said devices only when brought to the same pressure as the high-pressure gas consuming device 4 and the low-pressure gas consuming device 5.

[0080] Thereby, when the natural gas is in a vapor state in the headspace 3 of the tank 2, the natural gas can be sucked into the supply circuit 6. Thereafter, the vapor-state natural gas flows through the first heat exchanger 13, takes in the calories generated by the gas circulating in the heat treatment circuit 8, and is then compressed by the compression device 7.

[0081] When it is intended to supply the high-pressure gas consuming device 4, all the natural gas in the vapor state is compressed by the compressor 7 and then circulated to the high-pressure gas consuming device 4 and supplied to the same device.

[0082] When it is intended to supply the low-pressure gas consuming device 5, the natural gas in the vapor state is compressed by the compressor 7 to the first compression stage 11. In this case, the natural gas in the vapor state reaches a pressure suitable for the low-pressure gas consuming device 5 before partially circulating in the first branch path 9 and then circulates again in the supply circuit 6 to the low-pressure gas consuming device 5 and is supplied to the same device.

[0083] When it is intended to reliquefy the natural gas in the vapor state, the natural gas is compressed to the second compression stage 12, circulates inside the second branch path 10, and is expanded by the control member 32.

[0084] Thereafter, the natural gas in the vapor state passes through the first heat exchanger 13 and is precooled, further expanded by the expansion member 15, and then passes through the second heat exchanger 16. In parallel with the above, the gas in the liquid state circulates in the cooling circuit 17, passes through the second heat exchanger 16, and can at least partially reliquefy the natural gas in the vapor state. In order to promote the reliquefaction of the natural gas in the vapor state, the natural gas in the liquid state is subcooled by passing through the third heat exchanger 19 and then can pass through the second heat exchanger 16. The subcooled natural gas may function to reduce the overall temperature of the natural gas in the liquid state by circulating to the orifice 30, or may function to reduce the pressure in the tank 2 by recondensing the vapor state by spraying the subcooled gas through the spray member 31.

[0085] At the outlet side of the second heat exchanger 16, when the natural gas is completely reliquefied, this natural gas circulates in the sixth branch path 28 without passing through the separation device 21, returns into the tank 2 through the cooling circuit 17, and can limit unnecessary heat input.

[0086] If the natural gas is only partially reliquefied, the natural gas circulates to the separation device 21. The liquid fraction circulates in the fifth branch path 27 through the second outlet 24, reaches the tank 2 via the cooling circuit 17, and then reaches the orifice 30. The vapor fraction circulates in the fourth branch path 26 through the first outlet 23 of the separation device 21 and reaches the supply circuit 6 upstream of the first heat exchanger 13, where it is consumed or reliquefied.

[0087] The natural gas may be consumed by the two gas consumption devices 4 and 5. Thus, the gas in the liquid state can also circulate inside the additional supply circuit 33. In particular, in cases where there is not enough gaseous gas in the headspace 3 of the tank 2, it can also circulate through the high-pressure passage 34 and / or the low-pressure passage 35.

[0088] In FIG. 3, the gas contained in the tank 2 is ethane. Although ethane contains a fraction of methane, this fraction is minimal. The high-pressure gas consumption device 4 can consume ethane, but this is not the case for the low-pressure gas consumption device 5, even at a suitable pressure.

[0089] Ethane may be sucked into the supply circuit 6. Then, the gaseous ethane flows through the first heat exchanger 13 and absorbs the calories generated by the gas circulating in the heat treatment circuit 8, and then is compressed by the compression device 7.

[0090] When intending to supply the high-pressure gas consumption device 4, all the gaseous ethane is compressed by the compression device 7 and then circulates to the high-pressure gas consumption device 4 and is supplied to the device.

[0091] When intending to supply the low-pressure gas consumption device 5, as described above, the gaseous ethane cannot be directly supplied to the low-pressure gas consumption device 5. For this purpose, the gaseous ethane must first pass through the heat treatment circuit 8.

[0092] If it is intended to reliquefy the ethane in the vapor state or indirectly supply it to the low-pressure gas consumer device 5, the ethane in the vapor state is compressed up to the first compression stage 11, circulated up to the first heat exchanger 13 inside the first branch path 9 and precooled, and further expanded by the expansion member 15, and then can flow through the second heat exchanger 16. In parallel with the above, the ethane in the liquid state can circulate in the cooling circuit 17, flow through the second heat exchanger 16, and at least partially reliquefy the ethane in the vapor state. To promote the reliquefaction of the ethane in the vapor state, the ethane in the liquid state is subcooled by flowing through the third heat exchanger 19 and then can flow through the second heat exchanger 16.

[0093] If it is intended to supply to the low-pressure gas consumer device 5, the expansion member 15 may be configured to expand the ethane in the vapor state, whereby the ethane, by flowing through the second heat exchanger 16, advances from this second heat exchanger 16 while maintaining the fraction of methane described above in the vapor state although mainly in the liquid state. Since methane has a lower reliquefaction temperature than ethane, the gas advances from the second heat exchanger 16 at a temperature included between the two reliquefaction points of the two gases.

[0094] Thereafter, the partially reliquefied ethane can circulate up to the separation device 21, and then the gas fraction, that is, methane, may be supplied to the low-pressure gas consumer device 5 by advancing through the first outlet 23 and circulating in the third branch path 25 up to the low-pressure gas consumer device 5. The ethane may be returned to the tank in the same manner as the above-described form.

[0095] If it is intended to completely reliquefy the ethane in the vapor state, the reliquefied ethane can reach the tank 2 directly through the sixth branch path 28 and the fifth branch path 27 without passing through the separation device 21.

[0096] If the ethane is only partially reliquefied, the ethane circulates to the separation device 21. The liquid fraction circulates in the fifth branch path 27 via the second outlet 24, reaches the tank 2 via the cooling circuit 17, and then reaches the orifice 30. If it is not intended to supply the low-pressure gas consuming device 5, the vapor fraction circulates in the fourth branch path 26 via the first outlet 23 of the separation device 21 and reaches the supply circuit 6 upstream of the first heat exchanger 13, whereupon it is consumed or reliquefied.

[0097] As described with reference to FIG. 2, the subcooled ethane circulating in the cooling circuit 17 may function to lower the overall temperature of the ethane in the liquid state by circulating to the orifice 30, or may function to reduce the pressure in the tank 2 by recondensing the ethane in the vapor state by spraying the subcooled gas through the spray member 31.

[0098] For the additional supply device 33, only the high-pressure passage 34 needs to function for supply, because the ethane cannot be consumed by the low-pressure gas consuming device 5.

[0099] FIG. 4 shows an alternative embodiment of the management system 1 according to the present invention. Only the differences from those described above will be explained. For the structural features and features related to functions common to both embodiments, refer to the descriptions of FIGS. 1 to 3.

[0100] The management system 1 shown in FIG. 4 is different from that described above in that there is no third heat exchanger that functions to cool the gas in the liquid state circulating in the cooling circuit 17.

[0101] Instead, an alternative embodiment of the management system 1 according to the present invention comprises an additional branch path 48 that extends to the tank 2 and is connected in parallel to the first branch path 9 at the first compression stage 11. Through this additional branch path 48, the gaseous gas in the vapor state flows through the heat exchanger 49, which is configured to perform heat exchange between the gaseous gas in the vapor state and the refrigerant fluid circulating in the re-liquefaction loop 50. At the outlet side of the heat exchanger 49, the re-liquefied gas circulates in the additional branch path 48 and is then returned to the tank 2.

[0102] Thus, for example, in cases of an overly small temperature difference or an overly large amount of gaseous gas in the vapor state, when the gaseous gas in the liquid state cannot be supercooled inside the cooling circuit 17, which leads to poor re-liquefaction of the gaseous gas in the vapor state flowing through the second heat exchanger 16, the additional branch path 48 and the heat exchanger 49 can be used.

[0103] In such a situation, it is reasonable to divide the compressed gaseous gas in the vapor state between the heat treatment circuit 8 and the additional branch path 48, whereby the gaseous gas in the vapor state can be efficiently re-liquefied. As a result, the efficiency is the same as that of the management system described in FIGS. 1 to 3. For the gas path inside the management system, refer to the descriptions of FIGS. 2 and 3 according to the properties of the gas.

[0104] Of course, the present invention is not limited to the examples described so far, and many adaptations may be made to the examples without departing from the scope of the present invention.

[0105] As described so far, the present invention has actually achieved the objective setting and proposes a gas management system that provides the consumption and / or re-liquefaction of the gas without being affected by the properties of the gas. According to the present invention, as long as the management system according to the present invention is provided, variations not described in this specification may be implemented without departing from the scope of the present invention.

Claims

1. A gas management system (1) housed in at least one tank (2) of a floating structure, which includes at least one gas consumption device (4, 5), - At least one gas supply circuit (6) of the gas consumption devices (4, 5), the supply circuit (6) comprises at least one compressor (7), the compressor (7) comprises at least two compression stages (11, 12), and is configured to compress the gas taken in vapor form from the tank (2) to a pressure that meets the requirements of the gas consumption devices (4, 5), - At least one heat treatment circuit (8) of the gas in vapor state that has been compressed by at least one compression stage (11, 12) of the compressor (7), - At least a first heat exchanger (13) configured to perform heat exchange between the gas in a vapor state circulating between the tank (2) and the compressor (7) in the supply circuit (6) and the gas in a vapor state circulating within the heat treatment circuit (8), - At least one cooling circuit (17) comprising at least one pump (18) configured to take in liquid gas from the tank (2), - At least a second heat exchanger (16) configured to perform heat exchange between the vaporized gas circulating downstream of the first heat exchanger (13) in the heat treatment circuit (8) and the gas circulating within the cooling circuit (17) In a management system (1) that includes, The heat treatment circuit (8) comprises at least a first branch (9) connected to the first compression stage (11) of the compressor (7) and a second branch (10) connected to the second compression stage (12) of the compressor (7), wherein the second compression stage (12) is located downstream of the first compression stage (11), and the first branch (9) and the second branch (10) merge at a confluence point (14) of the heat treatment circuit (8), characterized in that the management system (1).

2. The management system (1) according to claim 1, wherein the confluence point (14) is located between the compressor (7) and the first heat exchanger (13).

3. The control system (1) according to claim 1 or 2, wherein the heat treatment circuit (8) comprises at least one expansion member (15) located downstream of the first heat exchanger (13).

4. The management system (1) according to claim 3, wherein the expansion member (15) is disposed between the first heat exchanger (13) and the second heat exchanger (16).

5. The management system (1) according to claim 1 or 2, wherein the second branch (10) of the heat treatment circuit (8) is equipped with a control member (32).

6. The management system (1) according to claim 1 or 2, wherein the gas consumption device (4, 5) is a high-pressure gas consumption device (4), and the supply circuit (6) is configured to supply gas to the high-pressure gas consumption device (4) and / or the low-pressure gas consumption device (5).

7. The supply to the low-pressure gas consumption device (5) by the supply circuit (6) passes at least partially through the first branch path (9), the management system (1) according to claim 6.

8. The management system (1) according to claim 1 or 2, wherein the heat treatment circuit (8) comprises a separation device (21) having an inlet side (22) located downstream of the second heat exchanger (16).

9. The management system (1) according to claim 8, referencing claim 6, wherein the separation device (21) comprises a first outlet (23) configured to allow the gas in vapor state to exit the separation device (21), and the heat treatment circuit (8) comprises a third branch path (25) connecting the first outlet (23) of the separation device (21) to the supply circuit (6) of the low-pressure gas consumption device (5).

10. The management system (1) according to claim 9, wherein the heat treatment circuit (8) is located between the tank (2) and the first heat exchanger (13) and includes a fourth branch path (26) that connects the first outlet (23) of the separation device (21) to the supply circuit (6).

11. The management system (1) according to claim 10, wherein the separation device (21) includes a second outlet (24) configured to allow the liquid gas to exit the separation device (21), and the heat treatment circuit (8) includes a fifth branch path (27) connecting the second outlet (24) of the separation device (21) to the cooling circuit (17).

12. The management system (1) according to claim 11, wherein the heat treatment circuit (8) includes a sixth branch path (28) that connects the outlet from the path of the second heat exchanger (16), which is a component of the heat treatment circuit (8), to the fifth branch path (27).

13. The management system (1) according to claim 1 or 2, further comprising a third heat exchanger (19) configured to perform heat exchange between the liquid gas circulating inside the cooling circuit (17) and a refrigerant fluid circulating in the cooling loop (20).

14. The management system (1) according to claim 1 or 2, further comprising an additional branching path (48) connecting the first compression stage (11) of the compressor (7) to the tank (2), wherein the management system (1) further comprises a temperature exchanger (49) configured to perform heat exchange between the vaporized gas circulating in the additional branching path (48) and the refrigerant fluid circulating through the reliquefaction loop (50).

15. The control system (1) according to claim 1 or 2, wherein the cooling circuit (17) comprises at least one end component (29) opening into the tank (2), the end component (29) being an orifice (30) located on the sprayer member (31) and / or the lower part of the tank (2).

16. A floating structure comprising at least a tank (2) containing liquefied natural gas and a management system (1) according to claim 1 or 2.

17. A floating structure comprising at least one tank (2) containing ethane and a management system (1) according to claim 1 or 2.

18. A method for managing gas contained in at least one tank (2) of a floating structure, which is carried out by the management system (1) according to claim 1 or 2, during which time, - If the gas contained in the tank (2) is liquefied natural gas, the gas is circulated through the first branch (9) and / or the second branch (10) of the heat treatment circuit (8), or - If the gas contained in the tank (2) is ethane, the gas is circulated in the first branch (9) of the heat treatment circuit (8), and the circulation of the gas is blocked in the second branch (10). method.

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