AGENCEMENT POUR SECURISER L'EVACUATION ET LE SAUVETAGE EN CAS DE SOLLICITATIONS DUES A DES FUMEES, DES CHARGES THERMIQUES ET POLLUANTES

SYSTEM FOR ENSURING EVACUATION AND RESCUE FROM THE EFFECTS OF SMOKE, HEAT AND POLLUTANTS

Abrégé français

L'invention concerne un agencement permettant de sécuriser l'évacuation et le sauvetage, en cas de sollicitations dues à des fumées, des charges thermiques et polluantes, dans des espaces pourvus de longues voies de secours, tels que des exploitations minières, des installations de trafic souterraines, et analogues. A cet effet, ledit agencement exploite les propriétés d'un brouillard d'eau produit par des moyens utilisés, afin que l'air reste respirable pendant une longue période, au moins dans la zone située en dessous de la couche des gaz de fumée, et puisse être maintenu au moins clair, de sorte que le sens d'évacuation reste identifiable. Selon ladite invention, les buses de pulvérisation (3) produisant ledit brouillard d'eau, sont fixées le long d'arcs de pulvérisation (2) disposés sur toute la longueur de l'espace et/ou de ses voies de secours, les uns derrière les autres, perpendiculairement au sens d'évacuation, à la suite du profil d'espace libre de l'espace et/ou des voies de secours. Avec l'agencement en forme d'arcs des buses de pulvérisation (3) sur toute la longueur des espaces et des voies de secours, tout l'ouvrage d'art est divisé en sections, qui n'entravent pas le flux d'air (6) présent dans ledit ouvrage d'art, de sorte que le courant de fumée ou de substances nocives n'est pas retenu par le brouillard d'eau produit.

Abrégé anglais

The invention relates to a system for ensuring evacuation and rescue from the
effects of smoke, heat and pollutants in areas with long evacuation routes,
such as mining installations, underground transport systems, or similar. Said
system takes advantage of the characteristics of a mist of water, which is
generated by misting means, in such a way that the air lying in the area below
the layer of fumes can be respired for a long period of time and its clarity
can at least be maintained, so that the direction of evacuation remains
visible. According to the invention, the sprinkler nozzles (3), which generate
the mist, are fixed to sprinkler arches (2) that are positioned along the
entire length of the area and/or its evacuation routes, one behind the other,
transversally to the direction of evacuation, following the clearance contours
of the area and/or the evacuation routes. The arch-type arrangement of the
sprinkler nozzles (3) over the entire length of the areas and evacuation
routes divides the structural installations into sections, which do not impede
the basic air flow (6) present in the installation, in such a way that the
smoke or pollutant flow is not accumulated by the mist that is produced.

Revendications

8
claims
1. Arrangement for ensuring evacuation and rescue from the effects of smoke,
heat and pollutants from spaces with long evacuation routes, such as mining
installations, underground traffic systems, etc., by using mist generating
discharge devices,
characterized in that
the discharge devices (3) are installed along spray arches (2) which are
arranged over the entire length of the space and/or of its evacuation routes
one after the other and transversely to the direction of evacuation,
conformably fitted to the clearance contour of the space and/or of the
evacuation routes.
2. Arrangement according to claim 1,
characterized in that
the discharge devices (3) are aimed in the direction of the air flow (6)
prevailing in the spaces and/or evacuation routes.
3. Arrangement according to claims 1 and 2,
characterized in that
the spray cone (7) of the discharge devices (3) completely fill the cross-
section of the space and/or evacuation route in the vicinity of the spray
arch.
4 Arrangement according to claims 1 to 3,

9
characterized in that
the discharge devices (3) are attached swiveling to the spray arches (2).
Arrangement according to claims 1 to 3,
characterized in that
each of every two spray arches (2) is provided with discharge devices (3)
spraying in opposite directions, and that the water feed to the spray arches
is
reversible.
6. Arrangement according to claims 1 to 5,
characterized in that
in case of fire at least one spray arch (2) is activated in the direction of
flow of
the air downstream of the fire source (5).
7. Arrangement according to claims 1 to 5,
characterized in that
in case of fire, at least one spray arch (2) is activated in the direction of
the
flow upstream of the fire source (5).
There follow two pages of drawings.

Description

CA 02405564 2002-10-08
Arrangement for ensuring evacuation and rescue from the effects of smoke, heat
and pollutants.
The invention relates to an arrangement for ensuring evacuation and rescue
from
the effects of smoke, heat and pollutants from spaces with long escape routes
such as mining installations, underground transport systems and the like.
Sprinkler-equipped systems for firefighting and rescue from underground
spaces,
and more particularly from highway and railway tunnels, are often installed in
test
installations. However, the inadequacy of such systems has been demonstrated
both In accidents and in practical trials. The reasons for this can be found
in the
relatively large water drops and the speed at which they are discharged from
the
sprinklers, which renders them incapable of binding smoke and pollutant
particles. In fact, their high speed of discharge and their size perturb the
flow,
which may either be natural or induced by exhaust systems, of the layer of
smoke moving in the open air. This causes the layer of fumes to mix with the
more fume-free layer below it, reducing vision and breathing for both the
evacuees and the rescue personnel and thus making both the evacuation and
the task of the rescue personnel more difficult. in addition, the high water
intensities required with sprinkler systems lead to partial extinction of the
fire.
However, there is an extreme danger of flashback from those areas of the fire
already extinguished. Inflammable gases and vapors are propagated unnoticed
and re-ignite at the first opportunity. The deflagrations or even explosions
thereby
created have already shown devastating results in underground installations
such as transportation tunnels. This danger is particularly high in cases
where
inflammable fluids are joining the fire, as is frequently the case with
vehicle fires
in tunnels.
Significantly better suited for containment of the consequences of fires are
systems which operate on the basis of the procedure described in German
Patent DE-PS 195 14 923 C2 for ensuring evacuation and rescue from the

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effects of smoke and heat. The principle underlying this invention consists in
reducing the smoke and pollutant concentration by extremely fine water
droplets
or water mist, hereinafter called simply "mist," in order to improve breathing
and
vision in the area of hazard so that evacuation and rescue from the tunnel is
considerably facilitated. Furthermore, the descending, fire-inhibiting mist
acts to
avert a sporadic, spatially limited extinction of the fire. This is achieved
by means
of a mist having lower discharge and/or propagation speed, and whose particle
density possesses the concentration required to bind the smoke, heat and
pollutants. The particle size of the mist is set in such a way that the water
particles sink slowly from their point of departure without affecting the
visibility in
the space. The water mist nozzles are arranged in the upper area of the tunnel
along its ceiling in the same way as sprinkler systems, so that their
direction of
spray can be varied in a direction parallel and perpendicular to the ceiling.
A
sectional arrangement of water mist nozzles enables them to be operated in a
pulsed sequence. Installed sensors detect the fire and trigger the mist
nozzles
installed in the immediate vicinity of the fire.
Practical trials have in fact demonstrated significant advantages over
traditional
sprinkler systems, but this mode of operation still did not satisfactorily
achieve
the desired effect. And it has the disadvantage that the natural flow of the
smoke
layer was still too strongly affected by the emerging mist and that it
consequently
became mixed with the low-smoke layer, although the cleansing effect of the
fine
mist droplets on the smoke was demonstrably present.
Another form known to art for combating smoke in enclosed spaces is the
application of water curtains. To achieve this, extinguishing agent spray
devices
are arranged so that in case of fire the agent being discharged forms a
curtain
which is impenetrable to fumes. But in this case a sufficient effect is
achieved
only in combination with high-performance fume extraction devices, which must
then be fitted for the entire space that is partitioned off between the water
curtains. Aside from the high expense this requires, systems of this kind are

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unsuitable for the evacuation and rescue of persons, since orientation is
absolutely impossible within such a space. As already mentioned, water curtain
divisions are always simultaneously linked with high-performance fume
extraction
systems. The spray system must thus always be arranged in such a way that at
least one fume extraction system is located between them. In this way the
space
between two water curtains can quite possibly extend up to 100 m.
The problem solved by the invention is an arrangement for ensuring evacuation
and rescue under the effects of smoke, heat and pollutants by using a mist
generating means which exploits the characteristics of the mist in such a way
that the air, at least in the region underneath the smoke layer, is breathable
over
a longer time and at least can be kept translucent so that the direction of
evacuation remains identifiable.
According to the invention, the problem is solved by the characteristics of
the first
claim. The following claims 2 and 3 refer to practical embodiments of the
arrangement.
The entire structural installation is divided into sections by the arched
arrangement, according to the invention, of the spray mist nozzles over the
entire
length of the spaces and evacuation routes. These sections are not, as in the
case with water curtains, areas partitioned off from each other, but rather
allow
the smoke or pollutant flow to be freely drawn off in the direction determined
by
the air flow present in each case and not affected by the water mist. This
means
that neither the arrangement of the spray arches transversely to the direction
of
the air flow nor the mist issuing from the nozzles impedes the air flow, which
travels along with the smoke and pollutant flow, unaffected, in its natural or
forced direction. The lower discharge force of the mist produces less
turbulence
in the smoke. Indeed, the mist nozzles, aimed in the direction of flow of the
smoke and pollutant stream, support that flow. At the same time, the floating
water droplets bind the dust, soot and pollutant particles contained in the
smoke

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and sink to the floor with them. This is equivalent to a process of washing
the
smoke, which in this way becomes cleaner, that is, more transparent, more
breathable and also cooler from section to section. The slow settling of smoke
cleaned in this manner as the distance from the source of the fire increases
is at
that point less dangerous to persons. The generally damp atmosphere in the
tunnel has a fire-inhibiting and ignition-inhibiting effect.
The arrangement of mist nozzles on each spray arch stems from their spray
characteristics. The spray cones must slightly overlap each other, so that all
spray cones cover the cross-section of the tunnel in the vicinity of the arch
The interval between spray arches inside the tunnel depends on structural,
safety
and, not least, on economic considerations. The closer the interval, the more
thoroughly will the gas stream be cleaned, and the more safe and successful
the
evacuation and rescue will be. At larger intervals, of course, the
reasonableness
of the length of the evacuation route must be taken into account.
When the system is operated in cases of accident, it is advantageous to
activate
one spray arch upstream of the fire source, so as to impede fire and smoke
propagation against the air flow. The number of the spray arches arranged to
aim
in the direction of the air flow downstream of the fire source depends on the
intensity of development of smoke and noxious gases.
A swiveling arrangement and control of the angle of discharge of the mist
nozzles
permits selective adaptation of the mist discharge to the flow conditions in
the
evacuation route to be protected. By adapting the direction of spray of the
mist
nozzles to the flow conditions, however, it is also possible to fit two
parallel spray
arches with mist nozzles spraying in opposite directions, and to incorporate a
controllable water feed.

CA 02405564 2002-10-08
By means of the arrangement according to the invention, and by making use of
relatively simple design means known to art, the characteristics of the mist
can
be exploited in such a way that the evacuation and rescue from spaces with
long
evacuation routes becomes significantly safer.
In what follows the invention will be more fully explained by means of a
typical
embodiment. In the annexed figures,
Fig. 1 shows schematically an arrangement according to the invention installed
in a tunnel following outbreak of fire, but before it is fully activated,
and
Fig. 2 shows the arrangement according to the invention in operation after the
outbreak of fire.
The arrangement described in the present embodiment also provides very
efficient and cost-effective fire detection, which though not the object of
this
invention, still serves the means for the extraction and direction of the
smoke
gases according to the invention. in this connection, reference is made to
Patent
Application DE 198 588 77.1. The details and operation of the fire detection
will
not therefore be more fully detailed in the following description.
As can be recognized from Fig.1, three spray arches 2 are shown arranged in
the
section of a transportation tunnel 1, each of them carrying a quantity of
spray
nozzles 3. The spray nozzles 3 are arranged to swivel in such a way that they
can apply mist in a range between 0° and 90° to the direction of
travel of the
tunnel 1. As already mentioned, in normal operating status the spray nozzles 3
serve for the continuous extraction of tunnel gases for forwarding to a
detection
device, not more fully represented. The spray arches 2 are installed,
perpendicularly to the direction of traffic, on the clearance contour of the
transportation tunnel 1 and conformably to the shape of its walls. The
installation
of the arrangement therefore causes no restrictions on the height nor on the

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width of the space available for vehicle traffic. The spray arches 2 are
connected
to a water supply 4. This can be achieved without particular additional
expense if
a fire fighting water line has been installed in the tunnel.
On the floor of the transportation tunnel 1 can also be seen a fire source 5,
which
is causing heavy smoke development. This is propagated mainly in the direction
of the air flow 6 which prevails in the transportation tunnel 1, and in fact
below
the tunnel ceiling. A small portion of the smoke stream also moves against the
air
flow 6. Smoke development and propagation is designated by a cross-hatching
of short horizontal lines.
The operation of the invention will now be explained using the arrangement
represented in Fig. 2 in operation after detection of a fire. For clarity, the
drawing
shows only the central spray arch 2 and there only three of the spray nozzles
3 in
operation. The range and direction of the mist being discharged is made clear
by
the spray cone 7, represented as a spatial grid work. However, all three spray
nozzles 3 of all three spray arches 2 are in operation. It can also be seen
that an
active spray arch 2, seen in the direction of the air flow 6, is upstream of
the fire
source 5 and that both the other spray arches 2 are in place downstream of the
fire source 5. The activity of the spray nozzles 3 is shown for al! spray
arches 2
by means of the gray, gate-shaped areas 8 shown behind them. In fact, the
effect
of the spray nozzles 2 in action can be compared to or explained as a mist
gate.
Further, it can clearly be seen that the direction of spray of the spray cone
8 is
aimed in the direction of the smoke flow, that is, also in the direction of
the air
flow 6. Part of the spray nozzle 3 is aimed slantingly downwards. The effect
of
the three spray arches 2 as a mist gate for the smoke flow varies; the spray
arches 2 located upstream of the fire source 5 impede the passage of the smoke
against the air flow 6. That means that this area is kept smoke-free for fire
fighting and rescue crews. At the same time, the smoke stream, even before it
passes through the second spray arch 2, has already, under the effect of the
mist, released in a first instance some of the smoke and pollutants, which
sink to

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the floor with the mist droplets. Under the effect of the mist of the second
spray
arch 2, the smoke stream is freed a second time of the particles that impede
vision and respiration, and is further cooled down. The gradual cleaning
through
the effect of the mist of the spray arches 2 is shown by a progressively less
dense cross-hatching of the smoke stream in the area downstream of the
associated spray arch 2. In this example, the last cleaning takes place after
passing the third spray arch 2 under the effect of the spray discharged from
it.
This is represented in the figure by a further thinning of the cross-hatching.
Depending on the intensity of smoke development and on the effect of the mist,
the number of spray arches 2 to be activated can be selected appropriately.

Dessin représentatif