DE102014213745A1 - Method for detecting a leak - Google Patents

Abstract

A method for detecting a leak (60) in a container (52) and such a container (52) with a thermal camera (54) for carrying out the method are presented. With the thermal camera (54), a thermal image is detected, based on which a leak (60) can be closed.

Description

The invention relates to a method for detecting a leakage and a container having a device for detecting a leakage.

State of the art

The presented method is used in connection with containers or containers in which a medium, in particular a gas, is contained or guided. In leaks in the outer skin or wall of the container, which is referred to as leakage, the medium can escape. A leak, which is also referred to as a leak, is a hole or an opening in an object, in this case a container, to understand through which or solids, gases and liquids can enter and exit. The leak caused by leakage can lead to malfunction or even failure of the entire system and also bring a dangerous impact on people and the environment in the environment of the container. As an example of a system where leakage should be detected, a fuel cell system is considered herein.

A fuel cell system consists of an example used in motor vehicles galvanic cell (fuel cell), in which the chemical energy of a supplied fuel and an oxidizing agent is converted into electrical energy, and the necessary components for supply and removal of reactants and reaction products, for temperature control and for control and monitoring. This thus represents an energy conversion system in which hydrogen is used as fuel in many cases, which reacts with oxygen. In the fuel cell system, a plurality of components are thus provided in which hydrogen is held and / or guided and which therefore can be seen as a container in the sense of the application. A leakage of hydrogen due to leakage should be avoided, but must be recognized immediately in any case, since hydrogen is flammable.

For measuring the hydrogen temperature in a fuel cell system, sensors are currently used whose temperature sensors are in direct contact with the hydrogen gas. On the one hand, the sensor must be compatible with hydrogen and, on the other hand, the connection between the sensor and the gas-carrying line must be tight.

It should be noted that hydrogen is incompatible with many materials and z. B. leads to embrittlement of certain metals. Due to the small molecule size and viscosity of hydrogen, it is structurally extremely difficult to get the joints sufficiently dense. In addition, hydrogen can escape through the sensor housing itself.

In addition, there is the danger that manufacturing or installation errors can lead to a safety-critical release of hydrogen into the environment. Because of this, designing and manufacturing a reliable, robust and inexpensive temperature sensor is very difficult and expensive.

In order to check the leakage of hydrogen in a fuel cell system, however, hydrogen-sensitive sensors are placed at a location as high as possible in the system. If there is a hydrogen leak in the system, the escaping hydrogen rises. The hydrogen sensor can then detect the passing hydrogen.

The sensors for detecting a hydrogen leak are also very expensive. In addition, these hydrogen can only determine exactly at the sensor location. If hydrogen flows past the detection range of the sensor, it will not be detected. Detection also takes place by the time it takes the gas to progress from the leak to the sensor.

The publication US 5,763,765 describes a method for detecting perforations in a membrane. The membrane has two oppositely directed surfaces, the first surface of which is exposed to a first gas, for example hydrogen, and the second surface to a second gas, for example ambient air. The membrane separates the two gases from each other. Should there be a contact of the two gases due to a perforation in the membrane, this leads to an exothermic reaction in which heat is released, which is detected by an infrared sensor.

From the publication US 2006/0238741 A1 For example, there is known a method for visualizing an outgoing gas in which, based on Raman scattering, a shift of the wavelength of a laser with which a gas is irradiated is detected.

Disclosure of the invention

Against this background, a method with the features of claim 1 and a container according to claim 9 are presented. Embodiments result from the dependent claims and the description. It also describes the use of a thermal imaging camera to detect leakage in a container.

The sensor used, in this case the thermal imaging camera, detects, according to the presented method, a change in temperature, in particular a reduction in the temperature, which is due to a leak due to an escape of a gas out of a container.

A container is here understood to mean an article which has a cavity in its interior and is adapted to separate the contents in the interior from the environment. For this purpose, the container is at least partially tight against the medium which is accommodated in this. Containers are used to hold objects, such as gases or liquids for a certain time. The container may have one or more openings for the supply and removal of the objects to be accommodated therein. A container in the sense of this application is thus also a conduit or a pipe through which a medium, for example a gas, is passed. The sidewalls of the tube prevent leakage of the medium in this area.

A thermal imaging camera, also known as an infrared camera, is an imaging device that receives and evaluates infrared rays. Thus, a thermal imaging camera is able to make visible to the human eye invisible heat radiation in the infrared range.

The new sensor principle described works without contact and is not in direct contact with the hydrogen. Elaborate constructions for sealing and the use of hydrogen-resistant materials are therefore not necessary. Consequently, the security in the overall system increases, especially as there are fewer potential flaws. In addition, the sensor can be manufactured more cheaply. The sensor principle allows in design both a measurement of the hydrogen temperature and a detection of hydrogen leakage.

In the presented method, a thermal imaging camera is directed to a container or possibly an overall system, for example a fuel cell system or a fuel cell. In this case, the entire system comprises at least one container in which gas, in particular hydrogen, is contained. The temperature of the hydrogen-carrying parts can be measured directly. By software correction to the heat absorption of the materials used can thus be concluded directly on the temperature of the hydrogen. The escape of hydrogen leads to a concentrated temperature change of the gas and thus the environment in the region of the outlet. Leaking hydrogen can be detected directly in this way by the thermal imager.

On the one hand, the method has the advantage of detecting escaping hydrogen everywhere in the system under observation and not just at one point. On the other hand, a hydrogen leak can be detected early on the leak. The system can then react faster and the amount of hydrogen released is significantly lower than in previous detection measures. The presented method can also be used to detect the leakage of different gases in general. The prerequisite for this is that the gas undergoes a temperature change by expansion. Accordingly, for example, the leakage of methane as a component of natural gas in CNG vehicles can be detected. If several different gases are conducted in a system, it is also conceivable to distinguish them by the different temperature changes.

If, for example, gas A emerges, the thermal imaging camera at the exit point sees a different temperature than with gas B. The system can then react accordingly. Thus, it is conceivable that when an explosive gas exits a corresponding emergency reaction is carried out, whereas the escape of a harmless gas only leads to an error message and the availability of the system remains. The triggered reaction is thus dependent on the nature of the exiting gas. The prerequisite for this is that the two gases lead to different temperature changes and that the difference between them is large enough to be detected with a thermal imaging camera, so that a sufficient selectivity is given.

Likewise, a different reaction of the control unit is conceivable when the combustible gas has caught fire at the leakage point, so a strong warming is detected.

The presented method is basically usable in systems in which gases are passed whose temperature changes by expansion.

Further advantages and embodiments of the invention will become apparent from the description and the accompanying drawings.

It is understood that the features mentioned above and those yet to be explained below can be used not only in the respectively specified combination but also in other combinations or alone, without departing from the scope of the present invention.

Brief description of the drawings

1 shows a gas line with a conventional device for measuring a hydrogen temperature.

2 shows a schematic representation of an embodiment of an arrangement with a number of containers and a thermal imaging camera.

Embodiments of the invention

The invention is illustrated schematically with reference to an embodiment in the drawings and will be described in detail below with reference to the drawing.

In 1 is a gas pipe 10 shown in the hydrogen 12 is guided. It is still a sensor 14 shown to measure the temperature of hydrogen 12 serves. Because the sensor 14 in direct contact with the hydrogen 12 It is necessary to have an opening 16 in the wall of the gas pipe 10 provide, through which the sensor 16 protrudes. This can lead to leaks 18 at the transition between wall of the gas line 10 and the sensor 14 in the area of the opening 16 come, causing a leakage of hydrogen 12 can lead.

2 shows a simplified, schematic representation of an arrangement 50 , For example, a fuel cell system, in the four containers 52 are provided. In these containers 52 is, for example, contain hydrogen. At least one of the containers 52 may be formed as a gas line in which a gas, in particular hydrogen, is guided.

It is now the task, a leakage of hydrogen from one of the containers 52 determine. This is done by a thermal imaging camera 54 which detects thermal images and thus detects leakage of hydrogen, resulting in cooling of the hydrogen in this area. The thermal imager 54 is with a computing unit 58 connected. This is in this case outside the arrangement 50 provided, but also within the arrangement 50 be arranged. The arithmetic unit 58 evaluates the received image data and initiates measures if necessary. These can, for example, the issuing of a warning or switching off the arrangement 50 include.

In the embodiment shown is a thermal imaging camera 54 provided the four containers 52 supervised. Of course, there are also more thermal imaging cameras 54 be provided. This thermal imager 54 or the thermal imaging cameras 54 can or can at least partly inside or outside the arrangement 50 be provided. For example, each container 52 exactly a thermal imaging camera 54 or even more than a thermal imager 54 be assigned. The thermal imaging cameras 54 are preferably to be arranged and / or aligned so that they can monitor critical points with high sensitivity. In the arrangement shown 50 the container has 52 right a leak 60 , which is indirectly detected by the thermal imager via a temperature change, in this case a drop in temperature.

In principle, at least one thermal imaging camera is provided, which records at least one thermal image. Leakage can then be detected on the basis of a thermal image, if a temperature difference in an area in which the leak exists is detected to surrounding areas. Alternatively or additionally, a leak can also be detected by means of a series of thermal images recorded in particular in chronological sequence. The temporal sequence makes it possible to detect when there is a temperature change in an area in which there is a leak in the time frame of the recording of the thermal images.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• US 5763765 [0009]
• US 2006/0238741 A1 [0010]

Claims (10)

Method for detecting a leak ( 60 ) in a container ( 52 ), in which at least one gas is contained, and in case of leakage ( 60 ), at least one gas escapes, causing a change in the temperature in the area of the leakage ( 60 ), with at least one thermal imaging camera ( 54 ) placed on this container ( 52 ) is detected, at least one thermal image is detected, which makes it possible to detect the change in temperature and based on a leakage ( 60 ) close. The method of claim 1, wherein the leakage of the gas leads to a cooling, which of the at least one thermal imaging camera ( 54 ) is recognized. Method according to Claim 1 or 2, in which at least one thermal image is assigned to a computing unit ( 58 ), in which the at least one thermal image is evaluated. Method according to one of claims 1 to 3, wherein in the container ( 52 ) are contained, and the evaluation of the at least one thermal image is performed such that it is detected which of the gases exits. Method according to one of claims 1 to 4, in which exactly one thermal image is evaluated in order to prevent leakage ( 60 ) to recognize. Method according to one of claims 1 to 4, in which a series of temporally successive thermal images is evaluated in order to prevent leakage ( 60 ) to recognize. Method according to one of claims 1 to 6, wherein upon detection of a leakage ( 60 ) a reaction is triggered.  The method of claim 7, wherein the reaction is selected depending on the nature of the leaked gas. Container which is particularly adapted for carrying out a method according to one of claims 1 to 8 and for receiving at least one gas, wherein in the case of leakage ( 60 ), at least one gas escapes, causing a change in the temperature in the area of the leakage ( 60 ), with a thermal imaging camera ( 54 ) for receiving at least one thermal image of at least a portion of the container ( 52 ), which makes it possible to detect the change of the temperature and by means of this a leakage ( 60 ) close. Container according to claim 9, to which a computing unit ( 58 ), with which the at least one thermal image is to be evaluated.

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