EP1312392B1 - Method and device for extinguishing fires in tunnels - Google Patents

Abstract

To extinguish a fire in a tunnel (2), e.g. a road tunnel, the site of the fire is isolated by curtains (6,8) on a fire detection signal to give a zone (14) for action. An inert gas floods the zone through flow openings from an external gas supply (31), to reduce the oxygen volume to an inert level. Smoke and fumes are extracted by suction (25) without affecting the inert level. A control unit (23) is linked to sensors to assess the oxygen content in the zone e.g. a smoke detector (5) and oxygen monitor (22), and set the flow of fire extinguishing gas accordingly.

Description

The present invention relates to a method for extinguishing fires in tunnels or tunnel-like structures, in which in this tunnel or tunnel-like structures in response to a first control signal by means of separations an inerting space is formed, which includes the affected by the fire section of the tunnel or tunnel-like structure, and in which, in a further method step, the oxygen content in this inertization space is reduced by an abrupt introduction of an extinguishing gas to an inert volume. The invention further relates to a device for carrying out this method, with separations, by means of which the tunnel or the tunnel-like structure is subdivided into concentration areas, which form inerting, and at least one extinguishing gas reservoir outside the inerting, the fluidically via inlet openings with the Inertisierungsräumen connected is.

The DE 198 11 851 A discloses an inerting method for reducing the risk and extinguishing indoor fires and an apparatus for carrying out the method. In this case, it is provided that initially the oxygen content in the target space (inertization space) is lowered to a specific basic inerting level, and that in the case of a fire the already lowered oxygen content is further lowered to a specific full inertization level.

The EP 1 103 286 A1 relates to a device for fire fighting in tunnels, the device comprising a gas pipe acting as a reservoir for an inert gas and associated with this and referred to as sector valves opening fittings for the release of the inert gas via nozzles in a tunnel sector.

The term "tunnel-like structure", which is mentioned as an addition to the tunnels, are in the present case essentially mine shafts, tunnels or similar semi-open spaces to be understood, which are also referred to in the following for the sake of simplicity with the term "tunnel". The term "separations" in this case means concentration barriers, by means of which the tunnel can be subdivided into one or more regions in which or in which the oxygen concentration (or the quenching gas concentration) differs from that required in other areas of the tunnel in a measure necessary for the extinguishing effect. Such ranges of low oxygen concentration or high extinguishing gas concentration are referred to herein as "concentration ranges".

A method and a device of the type mentioned are, for example, from DE 199 34 118 C2 known. The basis of that known method and the device as well as the present invention is the so-called "inert gas extinguishing technology", as the flooding of a fire-prone or in fire space by oxygen-displacing gases such as carbon dioxide, nitrogen, noble gases and mixtures of these gases is called. These "inert gases", which are also referred to here as "extinguishing gases", are usually stored in special reservoirs compressed in adjoining rooms. If necessary, the extinguishing gas is then passed through a piping system and corresponding inlet openings in the relevant inerting space. It is known that the extinguishing effect of this inert gas technology is based on the principle of oxygen displacement. While the normal ambient air is known to consist of 21% oxygen, 78% nitrogen and 1% other gases, the natural nitrogen concentration in the relevant inerting space is further increased by discharging, for example, pure nitrogen, thereby reducing the oxygen content. It is also known that a extinguishing effect material-dependent then starts when the oxygen content drops below 15 vol .-%. In case of solid fires, the fires already suffocate when the oxygen content in the air has been lowered from 21 to 11% by volume. In liquid and gas fires, however, a decrease in the oxygen content below 3 vol .-% may be required.

Both with that from the DE 199 34 118 C2 known method and the associated device, as well as in the present Invention is thus formed by activating at least two separations an inerting space, said partitions foreclose the tunnel before and behind the fire against the rest of the tunnel relatively gas-tight. These separations can be formed by mechanical devices, these mechanical devices being lowerable or retractable bulkheads or louvred curtains, or else smoke curtains or, preferably, also "gas flow barriers" which function similarly to the air curtains in store entrance. The first mentioned control signal for activating the separations can be triggered for example by emergency switch or by initiative of a central monitoring station (eg tunnel guard, fire station), or automatically by a fire detection device, which will be discussed below.

The recent catastrophe in the Gotthard tunnel has again shown that smoke extraction in tunnels is one of the biggest problems. This applies in particular to tunnels used by vehicles, as vehicle tires usually nourish the fire there, which causes enormous smoke and also the formation of toxic vapors. Already in the previous catastrophes in the Mont-Blanc tunnel and in the Tauern tunnel it became clear that it was also the very strong heat development, but especially the enormous smoke, which made it impossible for days to approach the fire. In this problem, the present invention, as the object has been considered, a method and apparatus for extinguishing fires in tunnels or tunnel-like structures of the DE 199 34 118 C2 further develop known type such that the smoke problem is effectively solved in connection with the inert gas extinguishing.

This object is achieved by a method for extinguishing fires in tunnels or tunnel-like structures of the aforementioned Solved type in which a specifiable oxygen content in the inerting space is maintained by controlled further extinguishing gas supply in a third step.

The object is also achieved by a device for carrying out this method, which contains an oxygen measuring device which emits measurement signals to a control unit which regulates the supply of quenching gas and optionally fresh air or oxygen in an inerting space.

The present invention thus provides a method and a corresponding device with which a fire, as it raged, for example, in the Mont-Blanc tunnel, in the Tauern tunnel and most recently in the Gotthard tunnel, can be extinguished with the known and very effective inert gas extinguishing technology, and at the same time the measures for the effective removal of the resulting smoke can be made. Since, as explained above, the inertization space formed by the separations is a largely gas-tight space sealed off from the rest of the tunnel, and since the retention of the volatile oxygen concentration in the inertization space is very essential for the sustained extinguishment of the fire, this inertization space can not be subtracted without further smoke, since this would change the oxygen concentration or the extinguishing gas concentration in the inerting unintentionally. Thus, with the method according to the invention, the oxygen content in the inerting space is constantly measured and if necessary quenching gas is introduced into the inerting space. Thus, a possible loss of quenching gas can be compensated by a flue by tracking quenching gas. Thus, the advantages of a modern and effective inert gas extinguishing technology are applicable to tunnel fires despite a strong development of flue gas or poison gas.

For this purpose, the device according to the invention provides an oxygen measuring device which emits measuring signals to a control unit which regulates the supply of extinguishing gas and optionally fresh air or oxygen into the inerting space.

Advantageous developments of the invention are specified in the subclaims.

Thus, for example, in a further method step, it is provided for the method according to the invention that a smoke extraction device is activated in the inertization space as a function of a second control signal. Of course, the smoke evacuation device need not be present in the inerting space itself; Rather, it can also be provided centrally or for two inertization rooms at the same time and only be connected to the rooms themselves via suction lines. It is important only that the performance of the smoke extraction device is tuned to the volume of 1 or 2 Inertisierungsräumen. Here, the second control signal in turn, as already described above for the first control signal can be triggered by emergency or by a central monitoring point, or automatically by a fire detection device, which will be discussed below. In any case, this second control signal, which reports a smoke, can also be used to stop the entry of other vehicles in the tunnel, in which, for example, a stop signal located at each tunnel entrance is activated.

Preferably, the first and the second control signal from a fire detection device, by means of which an assignment of the source of fire takes place to a plurality of passable sections of the tunnel or tunnel-like structure. For this purpose, a known per se fire detection device is provided, which is installed in the tunnel or tunnel-like structure such is that existing or incipient fires are nationwide detectable areas, and in the case of a detected fire or incipient fire by means of a detector, the first control signal for activating the separations and possibly the second control signal to activate the smoke evacuation device in the affected area. Here, the term "fire detection device" is preferably to be understood as an aspirative device in which a piping system with intake openings constantly sucked in representative portions of the tunnel air and fed to a detector for detecting a fire parameter. Here, the term "fire characteristic" physical quantities are to be understood, which are subject to measurable changes in the environment of an incipient fire or an already existing fire, such as the ambient temperature, the solid or liquid or gas content in the ambient air (formation of smoke particles or aerosols or Steam), or the ambient radiation. In the simplest case, the detector of such a fire detection device consists of a smoke sensor, which is then directed exclusively to the fire characteristic "smoke particles".

If the fire occurs on the boundary between two concentration spaces, it is detected by two adjacent fire detection devices, whereupon according to another embodiment of the method according to the invention a double inertization space is formed, which then consists of two adjacent concentration ranges. For this purpose, it is provided according to the method that the central separation between two adjacent passable sections of the tunnel or tunnel-like structure is not activated when the fire detection device responds in both sections.

As a further development, it is provided for the device according to the invention that each inertisation chamber is assigned a smoke sensor which transmits the first and / or the second control signal to the sensor Output control unit. The advantages of such a smoke sensor have already been explained above; of course, if such a smoke sensor is present in each inertization space, ie in each concentration range of the tunnel, this facilitates the localization of the source of the fire.

Preferably, the oxygen measuring device and / or the smoke sensor are part of the above-described aspirative fire detection device, resulting in a clear and compact fire alarm system.

The simplification of the device according to the invention and in particular the redundancy also serves a further development, according to which each of the described control units is assigned to each inertization space. In this case, it is preferably also provided that each control unit has further inputs for receiving command signals, which are output from a central monitoring point. Such a command signal may be, for example, "N ₂ , ie nitrogen full-flooding" to lower the oxygen content in the inerting further. This may be necessary when vehicle tires or fuel are burning. It is self-evident that the central monitoring station, for example the tunnel guard or a fire brigade headquarters, will only give the command for N ₂ -full-flooding if it is ensured that the affected inerting space has been evacuated. Such a command signal could also be "air or O ₂ -flutung". Such a command can be useful if the fire has been safely extinguished and the oxygen concentration must be quickly raised again to a safe level for living beings.

While in the method and apparatus according to the of DE 199 34 118 C2 formed prior art for each Inertisierungsraum an extinguishing gas reservoir is provided, it may well be advantageous, only a single central extinguishing gas reservoir to be kept, which is connected via a fluidic line network with each Inertisierungsraum. Such a central extinguishing gas reservoir can consist of an extinguishing gas cylinder battery, or else a side tube or another adjoining space of the tunnel forms the container for this extinguishing gas reservoir. In any case, the extinguishing gas reservoir must be dimensioned for the simultaneous flooding of two adjacent inertization spaces, namely in the event that the fire occurs on the boundary between two concentration spaces, in which case the double inerting space already described above is formed.

In the following a preferred embodiment of the invention will be explained in more detail with reference to a drawing.

Fig. 1

eine schematische Darstellung eines Tunnels, der mittels Abtrennungen in Konzentrationsbereiche unterteilt ist; und

Fig. 2

einen schematischen Teil-Längsschnitt durch einen Konzentrationsbereich eines solchen Tunnels, in welchem ein LKW brennt.

Show it:

Fig. 1

a schematic representation of a tunnel which is divided by means of separations in concentration ranges; and

Fig. 2

a schematic partial longitudinal section through a concentration range of such a tunnel in which a truck is burning.

Fig. 1 shows a schematic representation of a tunnel 2, at the tunnel walls 18 in the interior of the tunnel by way of example an aspirative fire detection device with suction lines 1 and therein provided suction 3 is arranged. These intake pipes 1 are arranged, for example, on both sides of a carriageway provided with the reference numeral 21 and indicated in the longitudinal direction of the tunnel 2 and fluidly connected to an outside of the passable tunnel tube or in the walls 18 arranged detector 5. The detector 5 is used in a known manner to monitor the sucked Air samples on fire characteristics and in turn is electrically connected to an evaluation unit 7.

The tunnel 2 is subdivided transversely to its longitudinal direction by a total of four partitions 4, 6, 8, 10 into three concentration regions 12, 14, 16. Of these separations, three, namely the partitions 4, 6 and 8, are completely lowered while the partition 10 is still in the semi-lowered state. Although mechanical separations in the form of rolling doors are provided in this example, it goes without saying that air curtains belonging to the state of the art can also be used for such separations. In any case, the separations seal the concentration regions 12, 14, 16 largely gas-tight against each other and against the rest of the tunnel and thus act as concentration barriers.

Outside each inertization space, extinguishing gas reservoirs 9, 11, 13, 15, 17, 19, which contain an extinguishing gas supply in the form of nitrogen at high pressure and are fluidically connected to inlet openings 20 in or at the tunnel walls 18, are arranged in the exemplary embodiment illustrated here.

The inventive method and in the Fig. 1 and 2 exemplified device for carrying out the method, the "inert gas extinguishing technology" advantage, so the flooding of a fire-prone or in fire room by an extinguishing gas, in the present case preferably nitrogen. In this case, the fire detection device 1, 3, 5, 7 detected by the detector 5 a fire, here for example in the concentration range 14. In response to a first Steersignals or in response to a second, actually to activate a smoke extraction device (25; Fig. 2 explained in more detail) the separations 6, 8 are activated immediately, that is lowered, so that an inerting space is formed with the concentration area 14, which encloses the area of the tunnel affected by the fire. At the same time, an inerting device is activated with the first control signal, which rapidly and very suddenly initiates extinguishing gas into the concentration range 14 from the storage containers 13 and 15 via the inlet openings 20. At the same time - what follows below Fig. 2 will be explained in more detail - the oxygen content in the concentration range 14 is constantly measured and ensured by a control unit that a once reached extinguishable oxygen or extinguishing gas concentration is maintained in the controlled extinguishing gas continues to be introduced into the concentration range 14. Thus, by rapid flooding with quenching gas, for example nitrogen, the oxygen content in the inerting space is reduced to an inert volume which is about 11% by volume in the case of solid firing and about 3% by volume in the case of liquid or gas firing.

Fig. 2 shows a schematic longitudinal section through a concentration range 14, as he basically the concentration range 14 of Fig. 1 corresponds, but is equipped with different types of separations 6, 8 and with an expanded technical equipment. It should first be noted that the in Fig. 2 shown burning truck with respect to the height of the passable tunnel tube is not shown to scale. Usually, only about 1 to 1.2 meters remain between the upper edge of a truck and the tunnel ceiling. For this in Fig. 2 illustrated concentration range 14, which in turn forms an inerting, are shown as partitions 6, 8, for example, two double air curtains, which belong to the prior art and are suitable to foreclose the concentration range 14 of the adjacent tunnel sections largely gas-tight.

Again, in the concentration range 14 of Fig. 2 a fire detection device having an intake pipe 1 and intake ports 3 provided therein is installed. About this intake air samples are constantly sucked from the interior of the concentration range 14, which is indicated by the vertically upward arrows. These air samples are fed to a detection and measuring unit, which consists of an oxygen measuring device 22, a detector 5 for detecting a fire characteristic, further comprising an evaluation unit 7 and finally a fan 24 for sucking the air samples. The oxygen concentration values measured by the oxygen measuring device 22 are delivered to a control unit 23, which compares the measured concentration value with a predetermined value and takes appropriate action. Also, the detector 5, when it has detected a fire parameter, via its evaluation unit 7, a first control signal to the control unit 23 from. This then activates the separations 6, 8, whereupon the concentration range 14 is largely sealed gas-tight against the rest of the tunnel. Furthermore, the control unit 23 sends a signal to the extinguishing gas reservoir 31 and starts by inert gas from this extinguishing gas reservoir 31 in the concentration range 14, the inerting process.

Detects the detector 5 and the fire characteristic "smoke", it outputs a second control signal to the control unit 23, whereupon this activates a smoke extraction device 25. At the same time, the oxygen measuring device 22 measures the oxygen content in the inerting chamber 14 and sends corresponding signals to the control unit 23, whereupon it continues to supply extinguishing gas from the reservoir 31 even after reaching the extinguishable oxygen concentration or extinguishing gas concentration by the predetermined low and extinguishable oxygen content in the inertization space 14, though the smoke extraction device 25 affects the composition of the gases within the room.

By further, for example, from a tunnel guard to the control unit 23 to be issued command signals 27, 28 either a Vollinertisierung or a supply of air or oxygen from additional storage containers 29, 30 causes.

Claims (10)

1. A method for extinguishing fires in tunnels or tunnel-like structures in which, subject to a first control signal, an area which is to be rendered inert is formed in said tunnel or tunnel-like structure by means of partitions which enclose the section of the tunnel or tunnel-like structure affected by a fire, and in which the oxygen content in said inerting area is lowered in a further method step to an inert level by the sudden introduction of extinguishing gas,
   characterized in that
   a predefinable oxygen content is maintained in the inerting area in a third method step by means of a further regulated supplying of extinguishing gas and that in a further method step, subject to a second control signal, a smoke extraction device (25) is activated in the inerting area.
2. The method according to claim 1, wherein the first and the second control signal issue from a fire detection device which provides an allocation of the seat of the fire to one or more sections of the tunnel or tunnel-like structure able to be rendered inert.
3. The method according to claim 2, wherein the middle partition between two contiguous sections of the tunnel or tunnel-like structure to be rendered inert is not activated when the fire detection device is activated in both of said two sections.
4. A device for realizing the method according to any one of claims 1 to 3 having partitions (4, 6, 8, 10) by means of which the tunnel (2) or tunnel-like structure can be divided into concentration zones (12, 14, 16) which form inerting areas and having at least one extinguishing gas reservoir (9, 11, 13, 15, 17, 19; 31) external said inerting areas in fluidic connection with the inerting areas by means of inlet openings (20),
   characterized by
   an oxygen-measuring mechanism (22) which sends measurement signals to at least one control unit (23) which regulates the supplying of extinguishing gas, and fresh air or oxygen as needed, to an inerting area, and by a smoke extraction device (25) which, subject to a control signal, is activated in said inerting area.
5. The device according to claim 4, wherein
   one smoke detector (5) is allocated to each inerting area which sends a control signal to the control unit (23) to form an inerting area by means of partitions and/or to activate the smoke extraction device (25).
6. The device according to claim 5, wherein
   the oxygen-measuring mechanism (22) and/or the smoke detector (5) are part of an aspirative fire detection device (1, 3, 5, 7, 24).
7. The device according to any one of claims 4 to 6, wherein
   each inerting area is allocated one control unit (23).
8. The device according to any one of claims 4 to 7, wherein
   each control unit (23) has inputs for receiving command signals (27, 28) as sent from a central monitoring site.
9. The device according to any one of claims 4 to 8, further comprising a network of pipes, by means of which a central extinguishing gas reservoir (31) is in fluidic connection to each inerting area.
10. The device according to any one of claims 4 to 9, wherein
    the central extinguishing gas reservoir (31), and/or also each further extinguishing gas reservoir (9, 11, 13, 15, 17, 19) respectively, is accommodated in one or a plurality of adjoining chambers or one such adjoining chamber itself constitutes the repository for the extinguishing gas reservoir.

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