Pressurized flammable gas tank

Abstract

Pressurized Flammable Gas Reservoir The invention relates to a pressurized flammable gas reservoir (1), such as hydrogen, comprising at least one primary cylinder (2) of pressurized flammable gas, said at least one primary cylinder (2) being individually equipped with a safety device (4) capable of automatically releasing the flammable gas contained in said at least one primary cylinder (2) to the open air in the event of detection of an overheating situation in the at least one primary cylinder (2), wherein the reservoir (1) further comprises at least one secondary cylinder (3) of pressurized fire extinguishing gas in fluidic connection with each safety device (4), a safety device (4) being configured to release fire extinguishing gas simultaneously with a release of flammable gas. Figure for the abstract: Figure 1

Description

Title of the invention: Pressurized flammable gas reservoir technical field

[0001] The invention relates to a pressurized flammable gas reservoir, such as hydrogen, preferably a gas storage system (or "Gas Storage System" in English, abbreviated GSS) type reservoir. Previous technique

[0002] Such a tank is, in a known manner, equipped with at least one safety device capable of releasing the flammable gas from the tank into the open air in the event of overheating detection. Indeed, under the effect of overheating near the tank, overpressure occurs and it is possible to create an explosion, which is very dangerous. However, the release of flammable gas remains dangerous because the released flammable gas can fuel a potential fire, the likely cause of the overheating.

[0003] Also, an approach is sought to accompany the release of the flammable gas, by making it non- or less dangerous, and by preventing it from being able to fuel a fire. Summary of the invention

[0004] For this purpose, the invention relates to a pressurized flammable gas reservoir, such as hydrogen, comprising at least one primary pressurized flammable gas cylinder, said at least one primary cylinder being individually equipped with a safety device capable of automatically releasing the flammable gas contained in said at least one primary cylinder to the open air in the event of detection of an overheating situation of the at least one primary cylinder, wherein the reservoir further comprises at least one secondary pressurized extinguishing gas cylinder in fluidic connection with each safety device, a safety device being configured to release extinguishing gas simultaneously with a release of flammable gas.

[0005] Specific features or embodiments, usable alone or in combination, are:

[0006] - a safety device is configured to release a volume of extinguishing gas greater than the volume of flammable gas released,

[0007] - a safety device is fitted so that the ratio of the volume of extinguishing gas the combined volume of flammable gas and extinguishing gas being less than 8%, preferably less than 4%,

[0008] - the ratio of the volume of extinguishing gas to the cumulative volume of flammable gas and The extinguishing gas is determined by the respective cross-sections of the extinguishing gas and flammable gas supply lines.

[0009] - the tank comprises a single secondary bottle,

[0010] - the extinguishing gas is an inert gas, such as: nitrogen, argon, helium,

[0011] - a safety device is capable of mixing flammable gas and extinguishing gas before to free them,

[0012] - a safety device includes a sensing element capable of detecting a overheating of a primary cylinder and a release element having a default closed position in which it seals the flammable gas and extinguishing gas lines and an open position in which it releases the flammable gas and extinguishing gas lines, the transition to the open position being controlled by the detector element,

[0013] - the detector element is confused with the liberating element and comprises an element a fuse that seals gas pipes and disintegrates when heated, thus releasing flammable and extinguishing gas from the pipes.

[0014] - the detecting element is distinct from the releasing element and is capable of controlling The release element in case of overheating detection and the release element includes at least one valve disposed across the flammable gas and extinguishing gas pipelines, said at least one valve being closed by default. Brief description of the drawings

[0015] The invention will be better understood upon reading the following description, given solely by way of example, and with reference to the figures in the appendix in which:

[0016] [Fig-1] Figure [Fig.1] shows, in schematic view, a reservoir, here a GSS,

[0017] [Fig.2] Fig.2 shows, schematically, the operation in the event of overheated,

[0018] [Fig.3] Figure [Fig.3] shows a safety device, according to a first embodiment,

[0019] [Fig.4] Figure [Fig.4] shows a safety device, according to a second embodiment,

[0020] [Fig.5] The [Fig.5] shows, a safety device, according to a third embodiment. Description of the implementation methods

[0021] The invention relates to a pressurized flammable gas tank 1. Such a tank 1 comprises, for example, hydrogen. It may, for example, be intended to be carried on a vehicle, with hydrogen being the fuel.

[0022] Such a tank 1 comprises at least one primary cylinder 2 of pressurized flammable gas. The tank 1 may comprise a single cylinder 2 of flammable gas. Preferably, as illustrated in [Fig. 1], the tank 1 is a GSS-type tank 1. A GSS-type tank 1 is a tank 1 comprising a plurality of primary cylinders 2. These primary cylinders 2 are generally fluidly interconnected so as to distribute the volume and pressure of the stored gas equally among all the primary cylinders 2, arranged parallel to one another. A rail connection typically allows such an interconnection. The GSS tank 1 then occupies approximately the volume of a parallelepiped.

[0023] If at least one primary cylinder 2 overheats, the pressure inside said primary cylinder 2 increases. If the overheating continues and no action is taken, there is a risk of explosion of the overheated primary cylinder 2. This explosion is a critical event that must be avoided. To this end, each primary cylinder 2 is individually equipped with a safety device 4. Such a safety device 4 is, in a known manner, capable of automatically releasing the flammable gas contained in the primary cylinder 2 so as to allow it to escape into the open air. A pipe 9 carries the flammable gas from the primary cylinder 2 to the safety device 4. A release pipe 10, at the outlet of each safety device 4, allows the gas to escape from the safety device 4 into the open air.

[0024] Such a release avoids the most critical event: the explosion of primary cylinder 2. However, this release disperses the contents of primary cylinder 2, namely a flammable gas, into the environment. Now, if primary cylinder 2 has heated up, it is because there is a hot spot, or even a bright flame, near it. Therefore, the flammable gas risks fueling an existing fire or even igniting upon contact with the hot spot. Thus, this release solves one critical problem, but creates a secondary problem that is only slightly less serious.

[0025] The invention aims to achieve a release of the flammable gas in the event of overheating or overpressure which does not pose the problem of risking a possible ignition of the released gas.

[0026] According to one feature, the tank 1 further comprises at least one secondary cylinder 3 of extinguishing gas. This extinguishing gas is stored under pressure in said at least one secondary cylinder 3. In the case of a GSS, said at least one secondary cylinder 3 advantageously takes the place of at least as many primary cylinders 2. However, it is not connected to the connection rail of the primary cylinders 2.

[0027] Furthermore, said at least one secondary cylinder 3 is in fluidic connection, via at least one pipe 8, with the inlet of each of the safety devices 4. A safety device 4 is configured to release extinguishing gas simultaneously with a release of flammable gas, namely in the event of detection of an overheating situation of the primary cylinder 2.

[0028] Figure 2 illustrates such a release. Overheating is detected in the leftmost primary cylinder 2. Consequently, its safety device 4 is triggered, releasing flammable gas from the primary cylinder 2 via pipe 9, combined with extinguishing gas from the secondary cylinder 3 via pipe 8. Both gases, flammable and extinguishing, are then released into the atmosphere via the release pipe 10. The black arrows represent the flammable gas flows, while the white arrows represent the extinguishing gas flows.

[0029] Here, it is assumed that only one primary cylinder 2 is overheating. The release process, independent for each primary cylinder 2 due to the independence of each safety device 4, would apply analogously to each overheating primary cylinder 2. Due to the common distribution of extinguishing gas, the latter would be distributed among all the safety devices 4, as needed.

[0030] According to another feature, a safety device 4 is configured to release a volume of extinguishing gas greater than the volume of flammable gas released. This is, at a minimum, necessary to guarantee and to comply with conditions preventing the flammable gas from self-exploding or self-igniting.

[0031] According to another feature, a safety device 4 is configured so that the ratio of the volume of extinguishing gas to the combined volume of flammable gas and extinguishing gas is less than 8%, preferably less than 4%. That is, Vex / (VEx+V1n) < 8%, respectively 4%, with VEX the volume of extinguishing gas and Vin the volume of flammable gas.

[0032] According to another feature, the ratio of the extinguishing gas volume to the combined volume of flammable gas and extinguishing gas is determined by the respective cross-sectional areas of the extinguishing gas and flammable gas supply lines. Thus, if the flammable gas volume is to be half the extinguishing gas volume, the flammable gas supply line 9 is shaped so as to have a cross-sectional area half that of the extinguishing gas supply line 8.

[0033] In the case of a GSS, the tank 1 comprises a number of primary cylinders 2 connected on a connecting rail. The number of secondary cylinders 3 can be arbitrary. The greater the number of secondary cylinders, the greater the safety, as it is possible to secure the tank 1 for a longer period: the extinguishing gas can accompany The longer the release of flammable gas, the more likely it is that tank 1 will be more securely protected: the flow rate of extinguishing gas released also increases with the number of primary cylinders 2 that are overheating. Conversely, dedicating a secondary cylinder 3 to storing extinguishing gas reduces the usable storage capacity, i.e., the storage capacity for flammable gas. Therefore, a compromise must be found between usable storage capacity and safety.

[0034] According to another feature, favoring usable capacity, the tank 1 includes a single secondary bottle 3.

[0035] The extinguishing gas can be any product, solid, liquid or gaseous, that limits or delays combustion. According to another characteristic, the extinguishing gas is an inert gas, such as: nitrogen, argon, helium.

[0036] It has been described that the extinguishing gas is released simultaneously with the flammable gas when overheating is detected. To better limit the risk of ignition of the released flammable gas, it is advantageous for the flammable gas to be released mixed with the extinguishing gas. Therefore, according to another feature, a safety device 4 is capable of mixing the flammable gas and the extinguishing gas before releasing them. This is illustrated later, with reference to Figures 3-5, with three embodiments of a safety device 4.

[0037] Generally, a safety device 4 comprises a sensing element 5 and a release element 6. The sensing element 5 is capable of detecting overheating of its primary cylinder 2. The release element 6 has a closed position in which it seals the gas lines and an open position in which it releases the gas lines. The closed position is the initial and default position. When the sensing element 5 detects overheating, it commands the release element 6 to open.

[0038] According to a first embodiment, more particularly illustrated in [Fig. 3], the detector element 5 is combined with the release element 6. The safety device 4 in this case comprises only a fusible element 7. This fusible element 7 initially seals the two inlet gas lines: the flammable gas line 9 and the extinguishing gas line 8. It thus performs the function of the release element 6 in the closed position. The fusible element 7 also performs the function of the detector element 5 in that, during overheating, its composition is such that the fusible element disintegrates. In doing so, it then performs the function of the release element 6 in the open position, allowing the passage for the gases, which, under pressure, then flow towards the release line 10. This line 10 also acts as a mixing chamber for the two gases, flammable and extinguishing, before their release.

[0039] According to another embodiment, more particularly illustrated in [Fig. 4], the sensing element 5 is separate from the releasing element 6. In this case, the sensing element 5 is capable of controlling the releasing element 6 in the event of overheating detection. In this case, the releasing element 6 may, for example, comprise a valve 11 arranged simultaneously across the gas pipes 8, 9. This valve 11 is initially closed and is closed by default. In the event of overheating, the sensing element 5 is capable of controlling the opening of the valve 11.

[0040] This alternative embodiment advantageously allows the detection to be relocated to a different point on the safety device 4, for example the other end of the primary cylinder 2. This is illustrated for example in [Fig.1], for the rightmost primary cylinder 2, with a detector element 5 disposed at the end of the primary cylinder 2 opposite to that which accommodates its safety device 4.

[0041] Figure 5 illustrates a variant of the embodiment of Figure 4. In the safety device 4 of Figure 4, a single valve 11 simultaneously closes the extinguishing gas line 8 and the flammable gas line 9. Alternatively, in the safety device 4 of Figure 5, the single valve 11 is replaced by a valve 12 closing the flammable gas line 9 and by a valve 13 closing the extinguishing gas line 8. The operation is identical to that described for the safety device 4 of Figure 4. Both valves 12 and 13 are initially closed and remain closed by default. In the event of overheating, the sensing element 5 is capable of simultaneously opening valve 12 and valve 13.

[0042] The invention has been illustrated and described in detail in the drawings and the preceding description. This description is to be considered illustrative and given by way of example and not as limiting the invention to this single description. Numerous embodiments are possible. List of reference signs

[0043] 1: reservoir,

[0044] 2: primary bottle,

[0045] 3: secondary bottle,

[0046] 4: safety device,

[0047] 5: detector element,

[0048] 6: liberating element,

[0049] 7: fusible element,

[0050] 8: fire extinguishing gas pipeline,

[0051] 9: flammable gas pipeline,

[0052] 10: release channel,

[0053] 11-13: valve.

Claims

Claims

1. Tank (1) of pressurized flammable gas, such as hydrogen, comprising at least one primary cylinder (2) of pressurized flammable gas, said at least one primary cylinder (2) being individually equipped with a safety device (4) capable of automatically releasing the flammable gas contained in said at least one primary cylinder (2) into the open air in the event of detection of an overheating situation of the at least one primary cylinder (2), the tank (1) further comprising at least one secondary cylinder (3) of pressurized extinguishing gas, in fluid connection with each safety device (4), a safety device (4) being shaped to release extinguishing gas simultaneously with a release of flammable gas,characterized in that a safety device (4) has a flammable gas supply pipe section (9) smaller than the extinguishing gas supply pipe section (8) so that it releases a volume of extinguishing gas greater than the volume of flammable gas released.,

2. Tank (1) according to claim 1, wherein a safety device (4) has a ratio of the cross-section of the extinguishing gas supply pipe (8) to the cumulative cross-section of the extinguishing gas supply pipes (8) and flammable gas (9) of less than 8%, preferably less than 4%, so that the ratio of the volume of extinguishing gas to the cumulative volume of flammable gas and extinguishing gas is less than 8%, preferably less than 4%.

3. Tank (1) according to any one of claims 1 or 2, comprising a single secondary bottle (3).

4. Tank (1) according to any one of claims 1 to 3, wherein the extinguishing gas is an inert gas, such as: nitrogen, argon, helium.

5. Tank (1) according to any one of claims 1 to 4, wherein a safety device (4) is capable of mixing flammable gas and extinguishing gas, before releasing them.

6. Tank (1) according to any one of claims 1 to 5, wherein a safety device (4) comprises a detector element (5) capable of detecting overheating of a primary bottle (2) and a release element having a default closed position in which it closes the flammable gas and extinguishing gas pipes and an open position in which it releases the flammable gas and extinguishing gas pipes, the transition to the open position being controlled by the detector element (5).

7. Tank (1) according to claim 6, wherein the detector element (5) is merged with the releasing element and comprises a fusible element (7) closing the gas pipes and disintegrating under heat so as to release the pipes of flammable gas and extinguishing gas.

8. Tank (1) according to claim 6, wherein the detector element (5) is distinct from the release element and is capable of controlling the release element in the event of detection of overheating and wherein the release element comprises at least one valve (11-13) arranged across the flammable gas and extinguishing gas pipes (8, 9), said at least one valve (11-13) being closed by default.

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