DE102013002777B4 - Device for storing gas under high pressure - Google Patents

Abstract

Device (1) for storing gas under high pressure, with at least one compressed gas container (2), with a valve device (3) and a safety blow-off device (4), and with a triggering unit (6) for the safety blow-off device (4), the triggering unit (6) has a pyro charge (9) for at least indirectly triggering the safety blow-off device (4), characterized in that the pyro charge (9) is connected electrically by means of at least one thermoelectric generator (7) for ignition.

Description

The invention relates to a device for storing gas under high pressure according to the type defined in more detail in the preamble of claim 1. The invention also relates to the use of such a device.

Devices for storing gas under high pressure are known from the general state of the art. They typically include one or more pressurized gas containers, each of which is provided with a valve device and a safety blow-off device with a release unit for the same. The containers are typically essentially cylindrical and are used to store gases under high pressure. In particular, pressurized gas tanks can be used to store hydrogen under nominal pressures of the order of 350 or 700 bar.

the DE 199 11 530 A1 describes a safety discharge device for such a compressed gas container. The safety release device described there is now generally known and customary. It essentially consists of a bursting body, which can be designed in particular in the form of a glass ampoule. This is filled with a liquid that has a very high thermal expansion coefficient. The bursting body holds a closure element in a sealing manner in a first position in an opening for pressure relief of the pressurized gas container. If thermal overheating occurs in the area of the safety venting device, the bursting body is destroyed by the internal pressure that develops in the area of the bursting body. It thus releases the closure body, which is moved by the internal pressure in the pressurized gas container from the line which it had closed. The gas can then flow out of the pressurized gas container through suitable openings in the area of the safety discharge device and the excess pressure can be released before it poses a potential risk of explosion.

The problem with this structure lies in the fact that there must be a local connection between the thermal load and the safety drain device. If a compressed gas container is used as a hydrogen tank in a vehicle, for example, then there is typically a valve for filling and removing the gas on one side of the compressed gas container and the safety discharge device is also arranged in its area. If, for example, a wheel fire occurs on the side of the compressed gas tank facing away from the valve, extremely high temperatures can occur in the area of the compressed gas tank without the bursting body on the opposite side being sufficiently heated to trigger the safety venting device.

The German patent proposes to remedy this problem DE 10 2006 009 537 B3 a compressed gas tank in particular for fuels. This compressed gas container contains a relief valve which is loaded with an appropriate pressure in order to keep it closed. The pressure is then in a line element, in particular a high-pressure hose, due to the medium enclosed therein at the relief valve. One or more thermal triggering units can be arranged in the area of the high-pressure hose, which in turn have a bursting body, for example. If there is a corresponding increase in temperature in the area of these triggering units, the respective bursting body will burst and release the medium from the high-pressure hose in the manner mentioned above. This flows into the environment and thus releases the relief valve, which opens the compressed gas accumulator. This makes it possible to install temperature monitoring not only in the area of the valve of the compressed gas tank, but also via the high-pressure hose in areas of the compressed gas tank that are remote from the valve.

In principle, this functionality is to be welcomed. However, the structure described in the German patent has three serious disadvantages. It works via a pressure drop in the high-pressure line. Destruction of the high-pressure line without this having occurred as a result of a thermal emergency also opens the relief valve and releases the gas from the compressed gas tank in an uncontrolled and possibly undesired manner. Another disadvantage is that the high-pressure hose can become trapped, for example when used in a vehicle, if an accident occurs. This means that pressure relief between the pinched area and the relief valve is no longer possible unless the high-pressure hose is accidentally destroyed in this area. If the pinching area is between the relief valve and the first release unit, the release unit may not function safely and reliably and the pressure vessel may remain closed contrary to the desired mode of operation. In addition, the safety device according to the patent can only monitor the areas in which bursting bodies connected to the high-pressure hose are arranged. If the area of the valve is also to be monitored, a further safety device, such as that described above, is necessary here. For monitoring a compressed gas tank on two or three Two or three bursting bodies with the corresponding closure elements are therefore required. This is complex, expensive and requires a comparatively large installation space.

For further general prior art, reference should also be made to the German Offenlegungsschrift DE 28 13 219 A1 be advised. This document describes a release fitting for a carbon dioxide container or the like, which is used in the event of a fire to drive window elements after thermal triggering by the gas in the carbon dioxide container in order to close them, for example. In order to be able to trigger this closing independently of a direct thermal effect in the area of the carbon dioxide container, a device is provided via which - electrically or mechanically from a distance - the bursting body closing this compressed gas container can be destroyed in order to avoid manual triggering of the to be able to accomplish the compressed gas driven facilities.

the DE 10 2010 006 516 A1 describes a device for storing a gas under high pressure in a vehicle with an active safety system, with a storage container and a device for emptying the storage container, which can be activated by an emptying signal from the active safety system, the device comprising at least one explosive charge.

From the other general prior art in the form of U.S. 2010/0001865 A1 a device for detecting smoke and flames is known from the field of building services. This device uses a so-called Seebeck sensor to detect fire or fire-induced heat. This Seebeck sensor, which can also be referred to as a thermoelectric generator, essentially works in reverse to a so-called Peltier element. With the Peltier element, heat or cold can be generated by applying voltage. In the case of the thermoelectric generator, an electrical voltage is generated by applying heat to one side of the thermoelectric generator and cooling the other side of the thermoelectric generator, which voltage can be evaluated in the case of the cited US publication in order to detect fire. The problem lies in the fact that the thermoelectric generator is typically designed to be very small and it is therefore difficult to achieve a sufficient temperature difference between one side and the other side. A thermocouple is therefore used in most cases in such applications, since such devices already have an electrical power supply for the detection of the smoke.

However, particularly when using pressurized gas tanks in vehicles, safety must also be guaranteed when the vehicle is not in operation. In this case, it cannot always be ensured that an adequate electrical power supply is available. This represents a serious disadvantage, since the safety function is severely impaired or can occur without an adequate electrical supply.

The object of the present invention is now to avoid these disadvantages and to specify a device for storing gas under high pressure, which can be implemented simply, efficiently and safely.

According to the invention, this object is achieved by the features in the characterizing part of claim 1. Further advantageous configurations of the device are specified in the dependent claims. A particularly preferred use is specified in claim 10.

Comparable to the devices according to the prior art, the device according to the invention for storing gas under high pressure comprises at least one compressed gas container and a safety blow-off device with a triggering unit for this. According to the invention, it is now provided that the triggering unit has a pyro charge for at least indirectly triggering the safety blow-off device, the pyro charge being electrically connected to at least one thermoelectric generator for ignition. One or preferably several thermoelectric generators can be distributed over the installation space of the device according to the invention. If they are heated, for example by flames or the heat generated by flames, they generate an electrical voltage which is then used very simply and efficiently to ignite the pyrolytic charge or explosive charge. This is then used to open the safety blow-off device, for example by blasting open part of a pipeline in the area of a predetermined breaking point, destroying a blocking body held in place by the blasting of a plug in the pipeline, or the like. The structure has the advantage that the thermoelectric generators can be used very easily and efficiently as sensors for strong thermal heating, for example by flames. They also ensure that they automatically generate the electrical voltage required to ignite the pyro charge when exposed to heat, so that no additional energy source is necessary, which could fail, for example, or whose energy content could be used up. The device according to the invention is therefore autonomous, safe and reliable even without being connected to an energy supply.

According to a very advantageous development of the device according to the invention, it can be provided that a zener diode is arranged in the electrical connection between the one thermoelectric generator and the pyro charge. Such a zener diode ensures a defined electrical voltage, as it is known that it only "switches through" above a predetermined limit voltage, and thus on the one hand ensures reliable electrical triggering of the pyro charge and on the other hand enables the pyro charge not to be accidentally triggered if the voltage is too low .

In a further extraordinarily favorable embodiment of the device according to the invention, it can now also be provided that the thermoelectric generator has a flat design, with a coating for ablation cooling being arranged on one of its surfaces. Such a coating for ablation cooling on one side of the flat thermoelectric generator enables the thermoelectric generator to function reliably. Regardless of which side the thermoelectric generator comes into contact with, for example, the flame or the thermal energy generated by the flame, this structure causes the coating to melt when exposed to heat. The melting of the coating requires a certain amount of thermal energy, which is at least partially withdrawn from the surface of the thermoelectric generator provided with the coating. This ensures that the surface provided with the coating for ablation cooling is actively cooled when the thermoelectric generator is exposed to heat and is therefore always cooler than the opposite surface, so that the generation of the desired voltage by the thermoelectric generator is guaranteed. In this case, the coating for ablation cooling can in particular be a low-temperature soft solder which is designed in such a way that it melts at a critical temperature for the device. This triggers the safety blow-off device at a temperature limit specified by the selection of the low-temperature soft mustard.

As already mentioned, it can be very favorable if several thermoelectric generators are distributed at different points of the device, since then monitoring can take place over a wide area. The problem that only one side of the device is heated and the triggering element is arranged on the other side and the safety blow-off device is not triggered as a result can thus be ruled out safely and reliably.

The device according to the invention can therefore be constructed in a correspondingly simple and reliable manner. It can ensure that the pressurized gas is released via the safety blow-off device both during operation of a system surrounding it and when such a system is at a standstill, since it does not have its own power supply and has an autonomously working safety monitoring system. It is therefore particularly suitable for use as a device for storing hydrogen in a vehicle that is operated with hydrogen as the fuel. Such a vehicle can be a fuel cell vehicle, for example, but also a vehicle powered by compressed hydrogen via an internal combustion engine. Due to the comparatively low density of hydrogen, compressed gas tanks with high pressure are necessary to ensure that the vehicle has a sufficient range. At the same time, these pressure vessels with hydrogen pose a certain risk, since they can burst, for example, in the event of an accident with a subsequent fire due to thermal expansion of the hydrogen, and parts of the vessel can be projected into the environment like bullets. It is therefore essential, especially in such applications, both during operation and when the vehicle is stationary, to have a good safety system in place that counteracts this problem by releasing the high-pressure hydrogen in critical situations in order to prevent the compressed gas tank from bursting avoid. This can be fulfilled in an ideal manner by the device according to the invention.

Further advantageous configurations of the device according to the invention result from the remaining dependent subclaims and are clear from the exemplary embodiment, which is described in more detail below with reference to the figures.

• 1 eine stark schematisierte Vorrichtung zum Speichern von Gas unter hohem Druck;
• 2 einen Schnitt durch eine mögliche Ausführungsform eines thermoelektrischen Generators;
• 3 eine erste mögliche Ausführungsform einer Sicherheitsabblaseinrichtung in einem ersten Zustand;
• 4 einer Sicherheitsabblaseinrichtung gemäß 3 in einem zweiten Zustand;
• 5 eine weitere mögliche Ausführungsform einer Sicherheitsabblaseinrichtung in einem ersten Zustand; und
• 6 die Sicherheitsabblaseinrichtung gemäß 5 in einem zweiten Zustand.

show:

• 1 a highly schematized device for storing gas under high pressure;
• 2 a section through a possible embodiment of a thermoelectric generator;
• 3 a first possible embodiment of a safety blow-off device in a first state;
• 4 according to a safety blow-off device 3 in a second state;
• 5 a further possible embodiment of a safety blow-off device in a first state; and
• 6 the safety blow-off device according to 5 in a second state.

In the representation of 1 a device 1 for storing gas under high pressure is shown in a highly schematic manner. This device 1 can be a tank unit in a fuel cell vehicle, for example. Typically, this tank unit will include multiple compressed gas tanks 2 in which the hydrogen is stored. In the representation of 1 such a compressed gas tank 2 is indicated. Each of the compressed gas tanks 2 has a valve device 3 and a safety blow-off device 4, which are indicated here in principle in the area of a connecting piece 5 on the compressed gas tank 2. The safety blow-off device 4 has a triggering unit 6, which in the area of the connecting piece 5 in the representation of FIG 1 is also indicated. In addition to the part arranged in the area of the safety blow-off device 4 , the triggering unit 6 also comprises a plurality of thermoelectric generators 7 which are connected via cables 8 to the parts of the triggering unit 6 arranged in the area of the safety blow-off device 4 . How they work will be discussed in detail later. In the part arranged on the safety blow-off device 4, the triggering unit 6 also includes what 1 however, cannot be seen, a pyro charge 9, via which an explosion can be generated when a predetermined electrical voltage is applied, which ultimately leads to the opening of the safety blow-off device 4. This is also described later in detail using two exemplary embodiments.

In the representation of 2 one of the thermoelectric generators 7 can now be seen in a schematic sectional view. The actual thermoelectric generator 7 consists of a plate-shaped material 10, which emits an electrical voltage at different temperatures on its underside and its upper side. It is connected to the cable 8 via the connection elements 11 , 12 in order to be able to conduct the voltage generated in the event of an activity of the thermoelectric generator 7 into the triggering unit 6 or to be able to use it to ignite the pyrocharge 9 . A zener diode 13 is provided in one of the connection elements 12 in order to ensure that the voltage is passed through the connection elements 11 , 12 into the cable 8 and thus to the tripping unit 6 or the pyro charge 9 only above a specific predetermined voltage. The zener diode 13 only turns on for a voltage when a correspondingly high voltage is achieved. This means that at the thermoelectric generator 7 there is a correspondingly high temperature or high temperature difference between one side and the other side of the sheet-like material 10 . Only above such a temperature does the Zener diode switch on the voltage, since the pyro charge 9 should only be triggered above such a high temperature. The zener diode 13 thus prevents false triggering at temperatures which are not due to the action of flames or the heat generated by a fire on the thermoelectric generator 7 .

In order to achieve safe and reliable triggering of the thermoelectric generator 7 above a predetermined temperature, it is now provided that one side of the sheet-like material 10, in the exemplary embodiment shown here the upper side, is provided with a coating 14. This coating 14 is used for ablation cooling and can, for example, be a low-temperature soft solder which melts at a predetermined temperature, for example in the order of magnitude of 200-400.degree. By melting the coating 14, heat is withdrawn from the upper side of the sheet-like material 10 of the thermoelectric generator 7, while the underside continues to be heated, for example by flames. In this case, a comparatively high voltage is generated by the thermoelectric generator 7 as a result of the temperature difference. This passes through the zener diode 13 and can trigger the pyro charge 9 via the triggering unit 6 . In a manner that will be described in more detail later, this then releases the safety blow-off device 4 in such a way that the hydrogen can escape from the compressed gas container 2 .

As it is from the representation of 1 as can be seen, several thermoelectric generators 7 , in the exemplary embodiment shown here 3 , can be arranged around the compressed gas tank 2 . This ensures that the effects of flames or thermal energy generated by a fire always trigger the safety blow-off device 4 safely and reliably, even if the flames occur, for example, on the side of the compressed gas container 2 facing away from the connecting piece 5 or in the middle thereof. In the case of devices 1 which have several pressurized gas containers 2, various thermoelectric generators 7 can be distributed over the entire device. These can all act together on one or all tripping units, so that when the temperature develops critically All pressurized gas containers 2 can be emptied via their safety blow-off devices 4 at one point within the device 1 .

In the representation of 3 a possible embodiment of the safety blow-off device 4 is shown as an example. This consists of a closed pipe end 15 which is in communication with the interior of the compressed gas tank 2 at its open end. In the exemplary embodiment shown here, a circumferential notch 16 is arranged around the circumference of the pipe end 15 as a predetermined breaking point. In the area of this notch 16 the already mentioned pyro charge 9 is arranged, for example in the form of a detonating cord inserted into the notch. This is correspondingly connected to one or preferably all thermoelectric generators 7 via the indicated cable 8 . If an electrical voltage above a predetermined value is passed into the area of the pyro charge 9 , this ignites and ideally bursts open the pipe end 15 along the predetermined breaking point designed as a notch 16 . This condition is shown in the 4 to recognize. The hydrogen can then be discharged through the now open tube end 15 and flows according to the arrows shown here and denoted by A.

Ideally, the hydrogen is discharged from the area of the device 1 via a further pipeline, for example when used in a fuel cell vehicle in a roof area or in another area in which there are typically no passengers.

A further alternative possibility for the realization of the safety blow-off device 4 is shown in the representations of FIG 5 and 6 again to recognize in the closed and open state. The structure essentially corresponds to the structure known from the prior art. A line end 17 connected to the interior of the pressurized gas container is tightly closed by a plug 18 . This stopper 18 is held in position by a glass ampoule 19 which can be easily destroyed. This essentially corresponds to the structure known from the prior art. There are openings 20 to the side of the glass ampoule 19, through which the gas can escape when the glass ampoule 19 is destroyed, as is shown in the illustration 6 can be seen, can flow according to the arrows A. In the area of the abutment for the glass ampoule 19 and/or in the area of one of the openings 20, in the exemplary embodiment shown here, as is shown in 5 can be seen, the pyro charge 9 is now arranged and connected to the thermoelectric generators 7 via the cable 8 . If at least one thermoelectric generator 7 heats up, there is a correspondingly high voltage in the cable 8, the pyro charge 9 is triggered and destroys the glass ampoule 19 pushed out or shot out of the line end 17, as in the representation of 6 can be seen. As already mentioned, the gas then flows out through the openings 20 . The abutment for the easily destructible glass ampoule 19 has the additional advantage that the stopper 18 is typically held up by the abutment and parts are thus prevented from flying around. A similar construction is also in the embodiment according to 3 and 4 conceivable, for example, a kind of cage which catches the part of the pipe end 15 that has been blown off.

All in all, the device 1 according to the invention thus offers a safety system that works safely and reliably, in addition to the described configurations of the safety blow-off device 4, other configurations which can be opened via a pyro charge 9 are certainly conceivable and familiar to the person skilled in the art.

Claims (10)

Device (1) for storing gas under high pressure, with at least one compressed gas container (2), with a valve device (3) and a safety blow-off device (4), and with a triggering unit (6) for the safety blow-off device (4), the triggering unit (6) has a pyro charge (9) for at least indirectly triggering the safety blow-off device (4), characterized in that the pyro charge (9) is connected electrically by means of at least one thermoelectric generator (7) for ignition. Device (1) after claim 1 , characterized in that the electrical connection between the at least one thermoelectric generator (7) and the pyro charge (9) has a zener diode (13). Device (1) after claim 1 or 2 , characterized in that the thermoelectric generator (7) is flat, with a coating (14) for ablation cooling being arranged on its one surface. Device (1) after claim 3 , characterized in that the coating (1) is formed by a low-temperature soft solder. Device (1) according to one of Claims 1 until 4 , characterized in that several thermoelectric generators (7) distributed at different points of the device (1). are, with all thermoelectric generators (7) interacting with the pyro charge (9) of the triggering unit (6). Device (1) according to one of Claims 1 until 5 , characterized in that the pyro charge (9) in the triggering unit (6) of the safety blow-off device (4) is provided for the destruction of a line cross-section at least indirectly blocking element. Device (1) after claim 6 , characterized in that the element blocking the line cross section at least indirectly is a glass ampoule (19) which holds a stopper (18) in the line cross section. Device (1) after claim 6 , characterized in that the element blocking the line cross-section at least indirectly is a plug which is connected to the pyro charge (9) and can be destroyed by it. Device (1) after claim 6 , characterized in that the element blocking the line cross-section at least indirectly is a line section with an end that is at least temporarily closed on one side and which is in operative connection with the pyrocharge (9). Use of the device (1) according to one of Claims 1 until 9 for storing hydrogen in a vehicle using the hydrogen as a fuel.

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