Storage facility for liquid state gas with tank and suction device for insulating layer of said tank

Abstract

The present invention relates to a storage installation (1) comprising a tank (2) for transporting and / or storing gas in liquid state and a gas consumer (3), said tank (2) comprising at least one insulating layer (5), said storage installation (1) comprising one device (4) for aspirating gas present in the insulating layer (5), said aspirating device (4) comprising a primary branch (6) fluidly connected to the gas consumer (3) and at least one secondary branch (7) fluidly connected to the insulating layer (5) of the tank (2) and through which gas from the insulating layer (5) flows, said aspirating device (4) comprising at least one suction member (8) configured to aspirate the gas flowing through the secondary branch (7).

Description

[Technical field]

[0001] The present invention relates to the field of gas storage facilities in liquid state, and more particularly to tanks for transporting and / or storing gas in liquid state arranged within such storage facilities. [Background technology]

[0002] In the industry of gas storage equipment in liquid state, during its transportation and / or storage, it is essential to keep this gas in liquid state and at a low temperature, said gas having a very low vaporization temperature. For this purpose, gas in liquid state is stored in tanks that include several layers of insulation, ensuring both impermeability by a sealing membrane and thermal protection by an insulating layer formed by an insulating box or insulating panels.

[0003] However, in exceptional cases, a leak can occur somewhere in the sealing membrane. The gas in liquid state flowing through the leak site will evaporate since it is no longer insulated. Monitoring systems exist to detect these leaks as early as possible and act accordingly.

[0004] The leaks can be extremely small. This type of leak is difficult to detect due to the insignificant loss of liquid state gas.

[0005] Furthermore, insulation spaces with gas leaks are decontaminated by inerting systems, which in some way imply a loss of the leaked gas and therefore the abandonment of the gas cargo, since this gas leak is released into the atmosphere rather than being used by the on-board gas consuming systems. Summary of the Invention

[0006] The present invention provides a solution for avoiding gas loss after minor leaks by providing a storage facility for gas in a liquid state comprising at least one tank for transporting and / or storing gas in a liquid state and at least one gas consuming device, said tank comprising at least one insulating layer, the storage facility comprising at least one device for aspirating gas present in the insulating layer, the aspirating device comprising at least one primary branch fluidly connected to the gas consuming device and at least one secondary branch fluidly connected to the insulating layer of the tank and through which gas from the insulating layer flows, the aspirating device comprising at least one suction member configured to aspirate gas flowing through the secondary branch.

[0007] By means of the suction device integrated in the storage facility, any evaporation of gas in the insulation layer due to minor leaks is taken care of by sucking said gas and using it as fuel for the gas consuming device. Thus, minor leaks are taken care of temporarily, since the gas is drawn off as it flows through the leak. Moreover, this loss of gas is avoided by the suction device, which ensures the recovery of at least a significant part of the leaking gas.

[0008] According to one aspect of the invention, all of the gas drawn in by the suction device is used as fuel and sent to the gas consuming device.

[0009] The tanks of the storage facility are suitable for transporting and / or storing gas in liquid state. The storage facility may be a vessel, such as an LNG tanker, capable of transporting a cargo of gas in liquid state to a destination for delivery of said cargo. The storage facility may also be a container ship, a gas-powered ferry or a bulk carrier, a floating liquid natural gas (FLNG) unit, a floating storage and regasification unit (FSRU), a floating storage barge, or a gravity support (GBS) platform for storing gas in liquid state. The insulating layer provides both sealing and insulation to keep the gas in the tank in liquid state and at low temperature. It is therefore understood that, in view of the precautions taken to transport and / or store gas in liquid state, it is very unlikely that a potential leak will occur in the insulating layer. However, the storage facility according to the invention makes it possible to overcome this possibility.

[0010] The gas consuming device can consume the gas from the tank. The storage facility can, for example, use the gas in liquid and / or vapor state exclusively as fuel or, in the case of a shipping vessel, use a portion of the gas cargo in liquid and / or vapor state as fuel. The gas in liquid and / or vapor state can also be used as fuel to supply electricity to the storage facility. The gas can also be led to a gas combustion unit where it is consumed, avoiding the outgassing of gases, for example methane, other hydrocarbon gases, dihydrogen or ammonia, into the atmosphere.

[0011] To be consumed by the gas consuming device, the drawn gas must contain fuel. For example, the gas contained in the tank can be liquefied natural gas (LNG), liquefied petroleum gas (LPG), ammonia, green hydrogen, hydrogen in liquid state, alcohol such as methanol or ethanol, or any other variant of the above gases produced from renewable energy sources.

[0012] According to a feature of the invention, a drive gas can flow through the primary branch, which by its circulation can participate in the suction generated in the secondary branch to suck gas coming from the insulating layer in case of a leak. By the secondary branch, which is fluidly connected to the insulating layer, the gas is sucked until it reaches the suction member, which circulates the gas through the primary branch to the gas consumer.

[0013] According to a feature of the invention, the suction member is an ejector having a first inlet connected to the primary branch, a second inlet connected to the secondary branch, and an outlet fluidly connected to the gas consumer, the ejector being supplied with a drive gas. When the suction member is an ejector, the drive gas flows through said ejector from the first inlet to the outlet. As the drive gas expands as it passes through the ejector, a pressure difference is created creating a suction at the second inlet and thus at the secondary branch.

[0014] The gas drawn into the secondary branch then joins the primary branch at the ejector outlet and mixes with the drive gas. The gas mixture then flows through the primary branch to the gas consumer.

[0015] According to a feature of the invention, the suction member is a compression member that suctions the gas flowing through the secondary branch, the compression member being provided with an outlet port fluidly connected to a gas consumer. For this reason, there are many types of compression devices, from pneumatic systems for inducing translational motion to electric or gas-driven systems for rotational motion. The outlet port allows the compression member to be fluidly connected to a gas consumer.

[0016] According to a feature of the invention, the compression member is supplied with a drive gas. The compression member is actuated, for example by being rotated by the flow of drive gas, thereby creating a suction force in the secondary branch to collect escaping gas. Once drawn in, the gas passes through an outlet port and is circulated to a gas consumer.

[0017] According to one feature of the invention, the driving gas may be dinitrogen. Dinitrogen is a fluid already produced and used on board ships as an inert gas for purging piping and inerting insulating layers. Thus, dinitrogen, for example for use as a working fluid, and more particularly the circuit in which dinitrogen circulates, has the advantage that, if the storage facility is provided with several tanks, it extends along all the tanks. Thus, as long as the dinitrogen circuit is within the range of the tank, it is easy to divert the function of inerting dinitrogen and use it as a driving gas for aspirating the gas in the insulating layer.

[0018] According to a feature of the invention, the compression member comprises a compressor and a power source for supplying the compressor. In such an arrangement, the operation of the compression member is performed electrically and not by a drive gas. Such a power source is an electric motor. An advantage of the compressor is that the drive gas is not supplied to the gas consuming device. The power source can be activated manually or automatically, for example when gas is detected in the insulating layer.

[0019] According to a feature of the invention, the secondary branch includes a check valve disposed between the insulating layer and the suction member. The check valve allows fluid flow from the insulating layer to the suction member but prevents any flow from the suction member to the insulating layer. The check valve thus prevents gas from flowing back into the insulating layer, e.g., undesirable circulation of the drive gas within the secondary branch or backflow of gas into the insulating layer.

[0020] According to a feature of the invention, the storage facility comprises a circuit for inerting the insulating layer, the secondary branch being connected to the inerting circuit, which comprises a valve isolating the secondary branch from the inerting circuit. The inerting circuit ensures the regeneration of the volume of inert gas in the insulating layer and also allows the evacuation of gases present in said insulating layer in case of a tank leak, for example methane, other gaseous hydrocarbons, dihydrogen or ammonia. The inerting circuit comprises a source of inert gas, for example dinitrogen, which is injected into the insulating layer. The inerting circuit then ensures, according to the invention, that the injected dinitrogen is removed from the insulating layer and circulated to the atmosphere or to the consumer.

[0021] To detect potential leaks in the insulating layer, the storage facility may, for example, be equipped with an analysis module connected to the inerting circuit and making it possible to detect the presence of a gas such as methane, an indication of a leak in the insulating layer.

[0022] Thus, the inerting circuit, in particular the outlet part to the atmosphere, can be branched off with a secondary branch, thus reducing the number of additional tubes necessary to design the storage facility according to the invention. However, branching off the secondary branch means arranging a valve in order to isolate the inerting circuit from the secondary branch. The inerting circuit may also comprise an additional valve. Thus, by opening one of the valves and closing the other valve, a fluid connection to the insulating layer can be made by the inerting circuit or by the suction device. This choice may depend, for example, on whether the gas is detected by an analysis module, if the latter is integrated into the storage facility.

[0023] According to a feature of the invention, the storage facility comprises at least two suction devices, the tank comprises a first insulating layer in contact with the gas in liquid state contained in the tank and a second insulating layer surrounding the first insulating layer, the secondary branch of the first suction device being fluidly connected to the first insulating layer and the secondary branch of the second suction device being fluidly connected to the second insulating layer. Each of the insulating layers comprises a sealing membrane and an insulating layer, which respectively ensure the impermeability and thermal insulation of the tank. Thus, the presence of two layers of insulation provides additional safety to the gas cargo in liquid state, both in terms of impermeability and thermal insulation. Since the possibility of the tank leaking is very low but not non-existent, the storage facility according to the invention can be configured to suction the gas in the two insulating layers to make the tank sufficiently safe. Each of the two suction devices is implemented in its own insulating layer. Both suction devices are fluidly connected to the gas consuming device, as well as to a source of drive gas, if the drive member of said drive device is operated by drive gas. The suction member of each suction device may thus be an ejector or compression member powered either electrically or by a drive gas, as described above.

[0024] According to a feature of the invention, the suction member is adapted to move at a maximum speed of 14 m / h. 3 It is designed to suck in + / - 25% of the gas. Therefore, a gas leak can cause the gas flow in the insulation layer to exceed 14 m / h. 3 If the gas becomes less than this, the escaping gas is at least partially sucked away and sent to the gas consuming device, thus reducing the dispersion into the atmosphere of greenhouse gases, in the case of methane, or harmful gases such as dihydrogen or ammonia.

[0025] According to a feature of the invention, the gas consumer is selected from an internal combustion engine, a gas boiler, a gas combustion unit and a generator. The gas consumer can thus use the gas from the tank and / or the leaking gas to ensure the propulsion of the storage facility in case it is to be moved or to ensure the power supply of said storage facility. The gas can also be fed to a gas boiler to generate steam and to supply power to a third party storage facility. If the gas consumer is a gas combustion unit, the leaking gas is burned and sent to the atmosphere.

[0026] Other characteristics and advantages of the present invention will become apparent from both the following description and from some exemplary embodiments, given for purposes of illustration and not limitation with reference to the accompanying schematic drawings. [Brief description of the drawings]

[0027] [Figure 1] 1 is a schematic diagram of a storage facility for gas in liquid state according to the present invention; [Diagram 2] 2 shows a tank for transporting and / or storing gas in liquid state and a device for suctioning the insulating layer of the storage facility shown in FIG. 1 . [Diagram 3] 3 represents an alternative installation of a storage facility according to the invention; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0028] FIG. 1 shows a storage facility 1 for gas in liquid state, comprising at least one tank 2 for transporting and / or storing gas in liquid state. In FIG. 1, three tanks 2 are shown, but the storage facility 1 can accommodate any number of tanks 2. In FIG. 1, the illustrated storage facility 1 is a ship. The gas in liquid state accommodated in the tank 2 can be, for example, a cargo to be transported by the ship to a given destination. The gas in liquid state can also be a simple fuel for the ship, the function of which is other than transporting a cargo of gas in liquid state. According to other examples, the storage facility 1 can also be a floating liquefaction unit, a regasification unit, a floating storage barge, or a gravity platform ensuring the storage of gas in liquid state.

[0029] The storage facility 1 comprises at least one gas consuming device 3. This device may be, for example, an internal combustion engine that ensures the propulsion of the storage facility 1 if it is intended to be mobile. The gas consuming device 3 may also be a generator that supplies power to the storage facility 1, a gas boiler that produces steam as energy for third-party consumers, or a gas combustion unit configured to burn gas. The gas consuming device 3 may consume the vapor gas contained in the tank 2 as fuel. If the gas needs to be in vapor state for consumption, the liquid state gas contained in the tank 2 may be evaporated. The evaporation of the gas may be the result of natural evaporation of the liquid state gas formed in the head space of the tank 2 or of forced evaporation to obtain fuel for the gas consuming device 3. The storage facility 1 according to the invention is characterized in that it comprises a suction device 4 that can use the evaporated gas or the liquid state gas once vaporized from the head space of the tank 2 and that can suck the vapor state gas located in the insulating layer of at least one of the tanks 2. The vapor state gas may enter the insulating layer of one of the tanks 2 in exceptional cases in which a leak occurs in said tank 2. The suction device 4 can then suck in this leaking gas in vapor state and circulate it to the gas consuming device 3 to supply it with fuel. The storage installation 1 according to the invention at least limits the loss of gas as a result of leakage and in the case of minor leakage at a relatively low flow rate the leaking gas can be at least partially sucked in and thus losses of the leaking gas can be avoided. All the gas sucked in by the suction device 4 is used as fuel and supplied to the gas consuming device 3.

[0030] Figure 2 shows the tank 2 and the suction device 4 in detail to better explain the suction device 4. Figure 2 also shows the insulating layer 5 of the tank 2. More specifically, the tank 2 comprises a first insulating layer 51 in contact with the liquid state gas 22 contained in the tank 2 and a second insulating layer 52 surrounding the first insulating layer 51.

[0031] Each insulating layer 5 comprises a waterproof membrane for sealing the insulating layer 5 and an insulating layer of an insulating box or insulating panel for insulating the liquid gas 22. The presence of two insulating layers 5 ensures an enhanced safety of the gas cargo 22 in the liquid state as well as maintaining the gas cargo at low temperatures.

[0032] As mentioned above, in exceptional cases, leakage of the first insulating layer 51 may occur despite all precautions being taken. In case of a major leakage, the leakage can be detected quickly and emergency measures can be implemented to ensure the safety of the storage facility and its occupants. In case of a minor leakage, it may be difficult to locate and the leakage amount is relatively small, but it should not be overlooked. Therefore, the suction device 4 is adapted to address the problem of gas leakage in the first insulating layer 51 in case of a minor leakage.

[0033] For this purpose, the suction device 4 comprises a primary branch 6, a secondary branch 7 and a suction member 8. The primary branch 6 is fluidly connected to the aforementioned gas consuming device 3 and the secondary branch 7 is fluidly connected to a first insulating layer 51.

[0034] The suction member 8 is an ejector 9, as shown in FIG. 2. The ejector 9 realizes a pressure difference to generate a suction force. For this purpose, the ejector comprises a first inlet 10, a second inlet 11, and an outlet 12. The first inlet 10 and the outlet 12 are connected to the primary branch 6, and the second inlet 11 is connected to the secondary branch 7. The primary branch 6 is further fluidly connected to a drive gas source 19 that circulates the drive gas through the primary branch 6. The drive gas flows through the ejector 9 via the first inlet 10 and then through the outlet 12. The properties of the ejector 9 allow to reduce the pressure of the drive gas passing through the ejector 9 and to create a pressure difference that leads to suction at the second inlet 11 and thus at the secondary branch 7.

[0035] Thus, if a leak causes gas evaporation in the first insulating layer 51, or leakage of gas in vapor state, the pressure difference created by the passage of the drive gas causes the gas to be sucked into the secondary branch 7 and flow via the second inlet 11 to the ejector 9. The sucked exhaust gas then mixes with the drive gas in the ejector 9. The mixture leaves the ejector via the outlet 12 and flows to the gas consumer 3, which consumes the sucked gas. The suction member 4 is adapted to suck up exhaust gas at a maximum speed of 14 m / h. 3 It is configured to draw in + / - 25% of gas and can at least partially compensate for the gas flow of the first insulating layer 51 in case of minor leaks.

[0036] The drive gas must flow in small quantities through the primary branch 6 so as not to affect the correct operation of the gas consuming device 3. As an example, an LNG ship engine can run for about 1800 m at a speed of about 12 knots. 3 / h of gas. The drive gas can be, for example, dinitrogen. The advantage of dinitrogen is that the dinitrogen flow can be implemented throughout the storage facility, including the tank 2 and the vicinity of the gas consuming device 3, for various functions, for example for use as an inert gas. It is therefore easy to divert the dinitrogen flow for use in the suction device 4. In FIG. 2 only one gas consuming device 3 is provided, but the suction device can provide several gas consuming devices 3.

[0037] The secondary branch 7 comprises a check valve 15 between the first insulating layer 51 and the suction member 8. The check valve 15 allows gas flow to be drawn from the first insulating layer 51 to the suction member 8 and prevents gas flow in the opposite direction. Thus, the check valve 15 prevents backflow of drive gas into the first insulating layer 51.

[0038] The storage facility further comprises an inerting circuit 16 that in particular makes it possible to regenerate the inert gas in the insulating layers 5 and also to evacuate potential hydrocarbons or ammonia or dihydrogen present in these same insulating layers 5. For this purpose, an inert gas, namely dinitrogen, is circulated by a dinitrogen source 20 within the insulating layers 5, in this case the first insulating layer 51. The gas contained in the latter is then sucked in and circulated within the inerting circuit 16, to be subsequently sent to the atmosphere 27.

[0039] The storage facility may include an analysis module 21 connected to the inerting circuit 16 which analyzes the gas drawn through the inerting circuit 16 for potential hydrocarbons or ammonia or dihydrogen which are indicative of a leak in the first insulating layer 51.

[0040] The inerting circuit 16 can be used in part to install the suction device 4, since it is potentially integrated in the storage facility in question. For example, it is useful to use tube openings in the first insulating layer 51 for both the inerting circuit 16 and the suction device 4, as shown in Figure 2. The drive gas source 19 and the dinitrogen source 20 can be one and the same source.

[0041] To isolate the inactivation circuit 16 from the suction device 4, the storage facility may comprise a valve 17 arranged in the secondary branch 7 and an additional valve 26 arranged in the inactivation circuit 16. When inactivation of the first insulating layer 51 is required, the additional valve 26 is opened and the valve 17 is closed so that the gas flowing through the inactivation circuit 16 flows to the atmosphere 27. When the suction device 4 is operated, the valve 17 is opened and the additional valve 26 is closed so that the suction member 8 can suck the gas circulating through the first insulating layer 51. The opening and / or closing of the valve 17 and the additional valve 26 can be performed depending on whether gas is detected by the analysis module 21 or not.

[0042] Figure 3 shows an alternative arrangement of the storage facility according to the invention, in particular the suction member 8 and the piping surrounding the tank 2. Only the features which differ from those described in Figure 2 are described here, and reference is made to the description of Figure 2 for the features common to Figures 2 and 3.

[0043] The variant differs from the one described in FIG. 2 in that the storage facility comprises two suction devices 4, namely a first suction device 41 which suctions gas into the first insulating layer 51 and a second suction device 42 which suctions gas into the second insulating layer 52, in the exceptional case where a leak leads to the presence of gas in liquid or gaseous state in the two insulating layers 5. Thus, all the elements of the suction device 4 are doubled and each of the insulating layers 5 can be treated by one of the suction devices 4. In FIG. 3, the two suction devices 4 are fluidly connected to one and the same gas consuming device 3, but it is also possible that each suction device 4 is fluidly connected to its own gas consuming device 3.

[0044] The inerting circuit 16 can also be doubled in order to inject dinitrogen into the two insulating layers 5. Thus, in FIG. 3 two dinitrogen sources 20 are shown, as well as two outlets to atmosphere 27, each of the inerting circuits 16 serving one of the two insulating layers 5. The storage facility may also comprise two analytical modules 21, each connected to one of the inerting circuits 16. Each analytical module 21 has the capability of detecting the gas in its own insulating layer 5.

[0045] According to the variant shown in FIG. 3, the suction member 8 of the first suction device 41 and the suction member 8 of the second suction device 42 are compression members 13 .

[0046] The compression member 13 of the first suction device 41 comprises a compressor 24 and a power supply 25. The power supply 25 supplies power to the compressor 24 to ensure its operation, e.g. a rotating operation, and thus to suck gas through the secondary branch 7. The compressor 24 comprises an outlet port 14 from which the sucked gas leaves to supply the gas consuming device 3.

[0047] Similar to the ejector 9 shown in Fig. 2, the compression member 13 of the second suction device 42 is also supplied with drive gas. It is the latter that drives the movement of the compression member 13, e.g. the rotational movement, and ensures the suction of the gas potentially present in the second insulating layer 52. Similar to the compressor 24, the compressor 13 has an outlet port 14 through which the suction gas and the drive gas leave to flow to the gas consumer 3. As shown in Fig. 2, the drive gas is derived from a drive gas source 19.

[0048] Each of the suction devices 4 shown in Figure 3 may incorporate any of the suction members 8 described above, i.e. one of the ejectors or compression members 13 described in Figure 2. Similarly, the suction device described in Figure 2 will also function if the suction member 8 is one of the compression members 13 shown in Figure 3.

[0049] Naturally, 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.

[0050] The invention, as just explained, achieves its intended purpose and makes it possible to propose a storage installation comprising a tank of gas in liquid state, a gas consuming device and a suction device for suctioning the gas escaping from the tank to supply the gas consuming device. Variants not described here can be implemented without departing from the context of the invention, since they comprise a storage installation according to the invention.

Claims

1. 1. A storage facility (1) for gas in a liquid state, comprising at least one tank (2) for transporting and / or storing gas in a liquid state and at least one gas consuming device (3), wherein the tank (2) comprises at least one insulating layer (5), the storage facility (1) comprises at least one device (4) for suctioning gas present in the insulating layer (5), the suction device (4) comprising at least one primary branch (6) fluidly connected to the gas consuming device (3) and at least one secondary branch (7) fluidly connected to the insulating layer (5) of the tank (2) and through which the gas flows from the insulating layer (5), and the suction device (4) comprises at least one suction member (8) configured to suction the gas flowing through the secondary branch (7).

2. 2. The storage facility (1) according to claim 1, wherein a drive gas flows through said primary branch (6).

3. 3. The storage facility (1) according to claim 2, wherein the driving gas is dinitrogen.

4. 4. The storage facility (1) of claim 2 or 3, wherein the suction member (8) is an ejector (9) having a first inlet (10) connected to the primary branch (6), a second inlet (11) connected to the secondary branch (7), and an outlet (12) fluidly connected to the gas consumer (4), and the drive gas is supplied to the ejector (9).

5. 2. The storage facility (1) of claim 1, wherein the suction member (8) is a compression member (13) that suctions gas flowing through the secondary branch (7), and the compression member (13) has an outlet port (14) fluidly connected to the gas consumer (4).

6. 6. The storage facility (1) according to claim 5, wherein the compression member (13) is supplied with the driving gas.

7. 7. The storage facility (1) according to claim 5 or 6, wherein the compression member (13) comprises a compressor (24) and a power supply (25) for supplying the compressor (24).

8. 3. The storage facility (1) according to claim 1 or 2, wherein the secondary branch (7) comprises a check valve (15) arranged between the insulating layer (5) and the suction member (8).

9. 3. The storage facility (1) according to claim 1 or 2, further comprising a circuit (16) for inerting the insulating layer (5), the secondary branch (7) being connected to the inerting circuit (16), the inerting circuit (16) comprising a valve (17) for isolating the secondary branch (7) from the inerting circuit (16).

10. 3. The storage facility (1) according to claim 1 or 2, comprising at least two suction devices (4), wherein the tank (2) comprises a first insulating layer (51) in contact with the gas in a liquid state contained in the tank (2) and a second insulating layer (52) surrounding the first insulating layer (51), wherein the secondary branch (7) of the first suction device (41) is fluidly connected to the first insulating layer (51) and the secondary branch (7) of the second suction device (42) is fluidly connected to the second insulating layer (52).

11. The suction member (8) has a maximum speed of 14 m / h. ３ 3. The storage facility (1) according to claim 1 or 2, adapted to draw in gases of + / - 25%.

12. 3. The storage facility (1) according to claim 1 or 2, wherein the gas consuming device (3) is selected from an internal combustion engine, a gas boiler, a gas combustion unit and a generator.

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