EP2046459B1 - Inertization method for reducing the risk of fire in an enclosed area and device for carrying out said method - Google Patents

Abstract

The invention relates to an inertization method for reducing the risk of fire in an enclosed area (10) and to a device for carrying out said method. The aim of the invention is to provide an inertization system for an enclosed area (10), by means of which an effective reduction of the risk of fire can be obtained as a result of a permanent inertization of the protection area (10) and by means of which said preventive fire-protection achieved by the permanent inertization can be restricted, if necessary, to spatially separate zones of the enclosed area, without requiring structural partitions. To achieve this, at least one inert gas, the gas density (ρGas) of which differs from the mean gas density (ρGas) of the ambient air atmosphere of the area (10) is introduced into the enclosed area (10) in such a way that in said area (10) gas layering of the first gas layer (A) and a second gas layer (B) occurs, the oxygen content of the first gas layer (A) corresponding substantially to the oxygen content of the ambient air atmosphere and the oxygen content of the second gas layer (B) corresponding to a specific establishable oxygen content that is reduced in relation to the oxygen content of the ambient air atmosphere.

Description

The present invention relates to an inerting method for reducing the risk of fire in an enclosed space and to an apparatus for carrying out the method.

It is known that in enclosed spaces which, for example, are only occasionally entered by persons and whose facilities react sensitively to the action of water, the risk of fire is minimized by lowering the oxygen concentration in the affected area to a value of, for example, about 12% by volume becomes. At this oxygen concentration, most flammable materials can no longer burn. Main fields of application are IT areas, electrical switch and distribution rooms, enclosed facilities as well as storage areas with high-quality commercial goods (see eg WO95 / 02433 ).

For example, from the German patent DE 198 11 851 C1 an inerting device for reducing the risk and extinguishing fires in enclosed spaces described. The known system is designed to reduce the oxygen content in an enclosed space to a pre-settable Grundinertisierungsniveau, and in the event of a fire or if needed, the oxygen content rapidly lower to a certain Vollinertisierungsniveau, thus effectively extinguishing a fire at the lowest possible storage capacity for To allow inert gas cylinders. For this purpose, the known device comprises an inert gas system which can be controlled by means of a control unit and also a supply pipe system connected to the inert gas system and the protective space, via which system the supply of inert gas provided by the inert gas system Inert gas is supplied to the shelter. As an inert gas is either a pressure bottle battery in which the inert gas is stored compressed, a system for generating inert gases or a combination of both solutions in question.

In the system of the type mentioned is a method or a device for reducing the risk and possibly extinguishing fires in the protected area to be monitored, also a Dauerinertisierung the shelter for fire prevention or fire fighting is used. As already explained, the mode of operation of an inertization method is based on the knowledge that in enclosed spaces the risk of fire can be counteracted by the fact that the oxygen concentration in the affected area is normally permanently lowered to a value of, for example, 12% by volume.

The prevention or extinguishing effect resulting from the inertization process is based on the principle of oxygen displacement. The normal ambient air is known to be 21% by volume of oxygen, 78% by volume of nitrogen and 1% by volume of other gases. To effectively reduce the risk of fire in a shelter, the concentration of oxygen in the room is reduced by introducing inert gas or an inert gas mixture, such as nitrogen. With regard to fire extinguishment of most solids, it is known, for example, that a extinguishing effect starts when the oxygen content drops below 15% by volume. Depending on the flammable materials present in the shelter, further lowering of the oxygen content to, for example, 12 vol.% May be required. In other words, by continuously inerting the shelter at a so-called "basic inertization level" where the oxygen content in the room air is lowered below, for example, 15% by volume, the risk of fire in the shelter is also effectively reduced can be.

As used herein, the term "base inertization level" is generally understood to mean a reduced oxygen level in the room air atmosphere of the shelter as compared to the oxygen level of the normal ambient air, but this reduced level of oxygen does not in principle imply any endangerment to persons or animals from a medical point of view - with certain precautions - may enter the shelter.

As already indicated, the setting of a basic inertization level, which unlike the so-called "full inertization level" does not have to correspond to such a reduced oxygen content in which an effective fire extinguishment already occurs, primarily serves to increase the risk of a fire developing in the shelter to reduce. The basic inerting level corresponds, depending on the circumstances of the individual case, to an oxygen content of, for example, 13% by volume to 15% by volume.

On the other hand, the term "full inertization level" is to be understood as meaning a further reduced oxygen content in comparison to the oxygen content of the basic inertization level, in which the flammability of most materials has already been reduced to such an extent that they can no longer be ignited. Depending on the fire load present in the affected shelter, the full inertization level is generally 11% by volume to 12% by volume oxygen concentration.

The hitherto known solutions, in which an inerting method for extinguishing fires or minimizing the risk of the occurrence of a fire are used, are designed for enclosed spaces, so that all goods stored in the enclosed space are integrated into the fire protection concept. Often, however, it is not necessary to permanently sterilize the entire volume of the enclosed space as a preventive measure since, for example, only certain areas of the room are used for the storage of combustible materials, while other areas of the room remain unused or where non-combustible materials are stored. In particular, in large warehouses, a permanent inerting of the entire storage space volume from an economic point of view only makes sense if in fact the entire volume of the room for the storage of fire-sensitive materials is used.

Since the consumer goods and food industry in particular is closely aligned with consumer behavior and changing consumer behavior has an immediate impact on the market, it is desirable for retailers to be able to react as flexibly as possible to storage and transport restructuring. Accordingly, warehouses are in demand whose storage capacity and storage condition can be adapted to the particular market situation in a particularly simple manner. This applies equally to inerting systems, which are often used in such warehouses as preventive fire protection.

Accordingly, the present invention based on the object to provide an inerting system (method and apparatus) for an enclosed space with which an effective mitigation of the risk of the formation of a fire can be achieved via a permanent inerting of the shelter on the other hand this with the Permanently inerting caused preventive fire protection can be limited to spatially separated zones of the enclosed space, if necessary, without this structural separations are required.

This object is achieved by an inerting process of the type mentioned in the present invention, that an inert gas or an inert gas whose gas density is different from the average gas density of the indoor air atmosphere of the enclosed space, is introduced into the enclosed space, that in the enclosed space without structural separation forms a gas layer consisting of a first gas layer, a second gas layer and a transition layer lying between the first and second gas layer, wherein the oxygen content in the first gas layer substantially corresponds to the oxygen content of the room air atmosphere, and wherein the oxygen content in the second gas layer certain, compared to the oxygen content of the room air atmosphere reduced, adjustable oxygen content corresponds.

With regard to the device, the object underlying the invention is achieved with an inerting to reduce the risk of the formation of a fire in an enclosed space, which is provided according to the invention that the inerting at least one inert gas source for providing an inert gas or an inert gas and a with a control controllable supply and Auslassdüsensystem for introducing the Inertgasquelle provided by the inert gas or inert gas mixture in the ambient air atmosphere of the enclosed space, wherein the inert gas or the inert gas mixture has a gas density which is different from the average gas density of the room air atmosphere enclosed space, and wherein with the aid of the supply and Auslassdüsensystems in a controlled manner, the inert gas or inert gas mixture is introduced into the enclosed space such that in the enclosed space without structural separation one from a he the glass layer, a second gas layer and a transition layer lying between the first and the second glass layer existing gas coating forms.

The device according to the invention is thus a possible realization by carrying out the inertization process according to the invention. In this realization, the oxygen content in the zone of the first gas layer substantially corresponds to the oxygen content of the room air atmosphere. On the other hand, the oxygen content in the zone of the second gas layer corresponds to a specific, compared to the oxygen content of the room air atmosphere reduced, adjustable oxygen content.

The achievable with the inventive solution advantages are obvious. Accordingly, in certain areas of the enclosed space, the products or goods to be stored can be accommodated without spatial separation and without costly insulation measures, so that the availability of the stored goods is always present, the oxygen content of the zones of the enclosed space to the fire and inflammation of the goods stored there is individually adjusted. For example, flammable or flammable goods are to be accommodated in the zone of the second gas layer, in which a relative to the room air atmosphere reduced oxygen content is set, while heavy flammable or non-flammable goods can be stored in the zone of the first gas layer. On the other hand, it is of course also conceivable that goods are stored only in the zone of the enclosed space in which the second gas layer is formed, while in the zone in which the first gas layer is present, remains unoccupied. This is useful, for example, if all goods to be stored in the enclosed space are sensitive to fire or highly flammable, although the storage capacity of the enclosed space is not completely exhausted with the goods to be stored.

The oxygen content in the zone of the first gas layer corresponds to the oxygen content of the room air atmosphere. Accordingly, an oxygen content of approximately 21% by volume is present in the first gas layer when the ambient air atmosphere at the time of formation of the gas stratification in the enclosed space has an oxygen content which corresponds to the oxygen content of the ambient air (ie approximately 21% by volume). equivalent. On the other hand, it is of course conceivable that the enclosed space at the time of formation of the gas stratification is already permanently inertized at a Grundinertisierungsniveau. For example, if a basic inertization level with an oxygen content of, for example, 15% by volume is already set in the enclosed space prior to the formation of the gas stratification, after forming the gas stratification, the zone in which the first gas layer is present would also have an oxygen content of 15 vol. -% exhibit.

By the term "inert gas" as used herein is meant any suitable gas that is chemically inert and has an oxygen displacement based extinguishing effect. The sting effect that can be achieved with inert gases occurs when it falls below the specific, material-dependent limit values required for combustion. As already stated at the outset, most of the fires extinguish when the oxygen content is reduced to 13.8% by volume. For this purpose, the existing volume in the second gas layer of the room air atmosphere must be displaced only by about 1/3 with the introduced inert gas, which corresponds to an inert gas concentration of 34 vol .-%. For fires that require significantly less oxygen for combustion, a correspondingly higher inert gas concentration is required, which is the case for example with acetylene, carbon monoxide and hydrogen. In particular, suitable inert gases according to the present invention are, in particular, the extinguishing agent argon, nitrogen, carbon dioxide or mixtures thereof (inergenes, argonites).

wobei ρ _Gas die Gasdichte in kg/m³, p der im Gas herrschende Druck in kPa, M die molare Masse des Stoffes in g/mol, R_m die allgemeine Gaskonstante (= 8,134 J/mol/K), und die T die absolute Temperatur in K ist.Furthermore, in the present specification, the term "gas density" is understood to mean the density of a gas which can be determined according to the ideal gas law. Thus, for the gas density plus the relationship given below: $${\mathrm{\rho }}_{\mathit{gas}}=\frac{p\cdot M}{R_m\cdot T}.$$

where ρ _{gas is} the gas density in kg / m ³ , p is the gas pressure in kPa, M is the molar mass of the substance in g / mol, R _{m is} the general gas constant (= 8.134 J / mol / K), and the T absolute temperature in K is.

Table 1 below shows an exemplary listing of the respective gas densities ρ _{gas of} various inert gases, which can be used in pure form or as a mixture in the solution according to the invention, for example. The data in the table refer to normal conditions, ie if a pressure p of 1013.25 hPa (= 1.01325 bar) and a temperature T of 273.15 K (= 0 ° C) is present. <u> Table 1 </ u> inert gas Density [kg / m ³ ] symbols helium 0,178 He nitrogen 1,251 N ₂ argon 1,784 Ar carbon dioxide 1,977 CO ² krypton 3,479 Kr xenon 5,897 Xe Air at 0 ° C 1,292

It can be seen that with the solution according to the invention, the running costs for providing a preventive fire protection, and thus the logistics costs of a storage operator can be lowered sustainably, since as a preventive measure not necessarily the entire volume of space with an inert gas or an inert gas mixture must be permanently inertized. Rather, without any structural measures having to be carried out, spatially separated zones with different, pre-determinable oxygen contents or inerting levels are formed in the volume of space. As a result, significant storage advantages can be achieved because both fire-prone products and products at risk of fire can be accommodated in a warehouse (enclosed space) without physical separation and without costly insulation measures.

The basic idea underlying the solution according to the invention can be seen in the physical stratification of gases of different specific density. Such gas stratifications are relatively stable and are ideally influenced, especially if no air flow or air circulation is provided in the enclosed space, primarily only by the diffusion flow of the gas particles present in the two gas layers. By suitable measures, which will be discussed in more detail below, it can be achieved that the diffusion coefficients of the respective gas particles are compensated accordingly, in order thus to maintain the gas stratification set in the enclosed space over a longer period of time.

The transition layer, that is to say the zone which exists between the first and the second gas layer, is the boundary layer provided between the two gas layers, the thickness of which is relatively small in relation to the thickness of the first and the second gas layer. In the transition layer there is a mixing of the gas particles present in the two gas layers, wherein this mixing is primarily due to the diffusion of the gas particles.

Advantageous further developments of the solution according to the invention are specified in the subclaims.

Thus, in view of a longer-term maintenance of the formed by the two gas layers storage zones in the enclosed space advantageously provided that formed in the enclosed space gas stratification by controlled addition of inert gas or an inert gas mixture in the second gas layer, and by suitable removal of Gas from the second gas layer and / or from the transition layer is maintained. This is therefore a measure with which the gas stratification counteracting the diffusion current is compensated in an effective manner.

Because of the law described by Boltzmann's Theorem of Gas Dynamics, according to which, due to the internal energy of the gas particles (entropy), both the diffusion of the gas particles present in the first gas layer and the diffusion of the gas particles present in the second gas layer are contained in the gas Counteracting gas layer formed in space, it is necessary to remove gas from the transition layer continuously or at predetermined times or events, wherein inert gas or an inert gas mixture of at least one of the two gas layers, for example the second gas layer, is simultaneously tracked in a controlled manner. By discharging gas from the transition layer, in particular the inert gas component diffused into the transition layer from the second gas layer is at least partially removed, in order to thus effect the cleanest possible separation between the first and the second gas layer. In particular, the thickness of the transition zone is kept at a low value.

On the other hand, simultaneously with the discharge of gas from the transition layer, a sufficient amount of inert gas is introduced into the second gas layer in a controlled manner, in order to ensure that the oxygen content in the zone of the second gas layer always certain, compared to the oxygen content of the room air atmosphere or the oxygen content of the first gas layer reduced oxygen content. In particular, with this measure, the spatial limit of the gas stratification gas layers is maintained in a particularly effective, yet easily realizable manner.

In a particularly advantageous realization of the solution according to the invention, it is provided that, after the gas stratification has been formed in the enclosed space, the temperature is determined either continuously in the zone of the first gas layer and secondly in the zone of the second gas layer, continuously or at predetermined times or events the determined temperature values of the zones of the first and the second gas layer are used to set a certain temperature difference between the zone of the first gas layer and the zone of the second gas layer and to maintain this temperature difference. Thus, with the advantageous development in the enclosed space without the use of a structural partition or the like, both zones (layers) having different oxygen contents and zones (layers) having different temperatures can be formed and held. It is particularly preferred that the lower layer of the two gas layers has a temperature lower than the upper layer of the two gas layers in order to achieve a temperature stratification, which is known to be extremely stable.

In this preferred development, since the zone of the upper gas layer, preferably the zone of the second gas layer, has a higher temperature with respect to the zone of the lower gas layer, preferably the zone of the first gas layer, with the temperature stratification, the maintenance in the enclosed space trained gas stratification continues to be supported. It should be noted that the gas density ρ _{gas of} the inert gas or the inert gas according to the above equation 1 is inversely proportional to the temperature T, so that in the case when the zone of the second gas layer is higher compared to the zone of the first gas layer Temperature, the density difference Δρ _gas between the inert gas used to form the second gas layer and the room air atmosphere forming gas is amplified.

The temperature measurement referred to in the last-mentioned further development takes place in a known manner, wherein it is particularly advantageous for the respective temperature measurement values to be at different positions in the enclosed space or in space to record the respective zones of the gas layers formed in the enclosed space in order to allow the most accurate and in particular redundant temperature determination.

The technical implementation for setting and maintaining the mentioned temperature difference between the first and the second gas layer can also be realized in different ways. In particular, it would be conceivable for the inert gas or inert gas mixture introduced into the enclosed space to form the gas stratification to be correspondingly heated or cooled beforehand in order thus to set a temperature in the zone in which the second gas layer is present, which is in comparison to the mean Temperature of the zone of the first gas layer is higher or lower. On the other hand, it would also be conceivable, by appropriate heating / cooling elements, which are arranged at suitable positions in the zones of the respective gas layers, to adjust or maintain the temperature difference. In particular, other solutions are conceivable here as well.

In order to ensure that the preventive fire protection measure provided by the solution according to the invention is reliably maintained for a longer time, it is provided in an advantageous further development that the oxygen content in the zone of the second gas layer is measured continuously or at predetermined times or events, and by controlled addition of inert gas or an inert gas mixture in the zone of the second gas layer, and by controlled removal of gas from the zone of the second gas layer and / or from the transition layer, the oxygen content in the zone of the second gas layer is maintained at the inerting pre-definable, and compared to the oxygen content of the zone of the first gas layer reduced oxygen content corresponds. Thus, it can be achieved that in the enclosed space in the zone in which the second glass layer is present, a Dauerinertisierung is set and maintained, in which - depending on the stored in the zone of the second gas layer or their flammability and their inflammatory behavior - a effective fire protection is ensured. It can be seen that the oxygen content of the zone of the second gas layer, which can be defined in advance and is reduced in relation to the oxygen content of the zone of the first gas layer, is adapted to the fire or ignition behavior of the goods to be stored or stored in this zone.

The measurement of the oxygen content in the zone of the second gas layer is carried out in the usual way, in particular, an aspirative operating system is suitable in which preferably at a plurality of locations in the zone of the second gas layer via a pipeline or duct system, a representative subset of the atmosphere actively sucked second gas layer and this subset is then fed to a measuring chamber with a detector for detecting the oxygen content. Of course, other solutions come into question here.

With regard to the inert gas or inert gas mixture used in the solution according to the invention, it is particularly preferred that this inert gas or inert gas mixture has a specific gas density ρ _gas which is different from the specific gas density ρ _{gas of} the room air atmosphere at the same temperature. As already indicated by way of example in Table 1, different inert gases come into question here. In particular, it is conceivable to use as the inert gas argon, carbon dioxide or krypton or xenon or mixtures thereof, ie gases whose gas density ρ _{gas is} higher than the gas density of "normal" air or higher than the gas density of the room air atmosphere of the enclosed space when the room air atmosphere at the time of formation of the gas stratification in the enclosed space has a chemical composition corresponding to the chemical composition of the normal ambient air.

In such a case, if the temperature of the zone of the second gas layer in which the inert gas was introduced to form the gas stratification is lower than the temperature of the zone of the first gas layer, that is lower than the temperature of the ambient air atmosphere, it forms in the enclosed space a particularly well-developed and stable stratification, in which the zone of the second gas layer is below the zone of the first gas layer.

On the other hand, it would of course also be conceivable, however, to take as inert gas, for example, nitrogen, helium or a mixture thereof, ie a gas whose average gas density is lower than the gas density of air. In this case, it is expedient, in particular in the case of the inert gas, to appropriately heat this inert gas prior to introducing the inert gas into the space or into the zone of the second gas layer, thereby further reducing its specific gas density, whereby gas stratification in the enclosed space can be achieved which the second gas layer is above the first gas layer.

In order to ensure that goods with different inflammatory behavior can be stored in the enclosed space, it is provided in a preferred development that not only in the zone of the enclosed space in which the second gas layer is formed, but also in the zone of the room, in which the first gas layer is formed, a Dauerinertisierung is formed. Specifically, it would be conceivable in this preferred development that prior to forming the gas stratification in the enclosed space by introducing an inert gas or an inert gas mixture, the room air atmosphere of the enclosed space is changed so that the oxygen content in the indoor air atmosphere is lowered to a certain Grundinertisierungsniveau, which a reduced compared to the normal atmospheric oxygen content (about 21 vol .-%) reduced oxygen content. By this measure, which is to be carried out prior to forming the gas stratification in the enclosed space, it is achieved that after forming the gas stratification in the enclosed space two spatially separate zones with different oxygen content are formed, wherein the respective oxygen contents of these two zones or Gas layers are reduced compared to the oxygen content of the normal ambient air. Thus, by a suitable choice of the basic inertization level, which is set before forming the gas stratification in the enclosed space, and by a suitable choice of the determined oxygen content, which is set in the formation of the gas stratification in the second gas layer, it is possible to determine the respective oxygen contents adjust the two gas layers forming the gas direction to an inerting level adapted to the goods to be stored in the respective zones.

In a preferred further development, in particular of the last-mentioned embodiment, provision is preferably made for the oxygen content in the first gas layer to be measured continuously or at predetermined times, and for controlled addition of inert gas or an inert gas mixture into the first gas layer and controlled removal of gas the first gas layer and / or from the transition layer, the oxygen content in the first gas layer is maintained at the Grundinertisierungsniveau. This is a suitable measure, with which it is achieved that the formed stratification is not dissolved over a longer time by the diffusion of the individual gas particles.

In order to achieve that the solution according to the invention be used not only as a preventive fire protection, but also as a measure to combat a fire can, is provided in a preferred development that preferably in the second gas layer continuously or at predetermined times or events at least one fire characteristic is measured, wherein in the case of detection of at least one fire parameter or fire by sudden introduction of inert gas preferably in the zone the second gas layer, the oxygen content in the second gas layer or in the entire volume of space is lowered to a Vollinertisierungsniveau, which corresponds to a compared to the certain inerting even further reduced oxygen content, and in which the flammability of the stored in the zone of the second gas layer goods can be effectively prevented or in which an effective fire extinguishing is possible. Of course, it would also be conceivable in the event of a fire, in addition to or as an alternative to setting the Vollinertisierungsniveaus initiate a chemical quenching gas in the room, the extinguishing effect is not based on the Stickeffekt. As a chemical quenching gas, for example, HFC-227ea or Novec ^® 1230 or a mixture thereof in question.

The term "fire characteristic" is understood to mean physical quantities which undergo measurable change in the environment of a fire of origin, e.g. the ambient temperature, the solid or liquid or gas content in the ambient air (formation of smoke in the form of particles or aerosols or vapor) or the ambient radiation.

The detection of the fire parameter preferably takes place with the aid of an aspirative intake pipe system, with which representative subsets, for example, the atmosphere of the second gas layer actively sucked and this subset is then fed to a measuring chamber with a detector for detecting a fire characteristic. Of course, other measures come into question here.

Alternatively or in addition to the aforementioned embodiment, it is also conceivable that in the zone of the first gas layer is measured continuously or at predetermined times or events at least one fire parameter, wherein in the case of detection of a fire characteristic by sudden introduction of inert gas or an inert gas or of an extinguishing gas into the zone of the first gas layer, the oxygen content in the first gas layer is lowered to an inerting level corresponding to a reduced oxygen content compared to the oxygen content of the room atmosphere, and in which the flammability of the goods stored in the zone formed with the first gas layer is effective is prevented.

Finally, with regard to the method according to the invention, it is still advantageous that the respective layer thicknesses, i. the thickness of the zone of the first gas layer and the thickness of the zone of the second gas layer are adjustable. With this development, a particularly fast and easy-to-implement expandability of the fire-protected zones in the room by flexible design of the respective gas layers in the storage room volume is possible.

In a device realization of the inventive solution, it is preferred that the outlet nozzle system has at least one displaceable in the vertical direction outlet nozzle, so that the vertical position or position of the second gas layer, and thus the position or position of the first gas layer in the enclosed space adjustable is.

It is also preferred that the device according to the invention for carrying out the inertization process further comprises a controllable via a control exhaust system to remove gas in a controlled manner from the second gas layer and / or in particular from the transition layer, while simultaneously via the outlet nozzle system in the zone of the second Gas layer inert gas is tracked, whereby the oxygen content in the zone of the second gas layer is maintained at the inerting, which corresponds to the determined oxygen content.

Fig. 1

eine erste bevorzugte Ausführungsform der erfindungsgemäßen Inertisierungsanlage; und

Fig. 2

eine zweite bevorzugte Ausführungsform der erfindungsgemäßen Inertisierungsanlage.

Hereinafter, preferred embodiments of the inerting system according to the invention will be described with reference to the accompanying drawings. It shows:

Fig. 1

a first preferred embodiment of the inerting plant according to the invention; and

Fig. 2

a second preferred embodiment of the inerting plant according to the invention.

In Fig. 1 a preferred embodiment of the inerting plant according to the invention for reducing the risk of fire in an enclosed space 10 is shown, this plant is particularly suitable for carrying out the inertization process according to the invention.

In the Fig. 1 schematically shown system has an inert gas source 20 for providing an inert gas or an inert gas mixture, which includes, for example, an inert gas 20a, in particular a nitrogen generator and a Gastlaschenbatterie 20b, in which under high pressure, an inert gas or an inert gas mixture is stored. An inert air compressor 20a 'is connected to the inert gas generator 20a. Via a controller 15, the air flow rate of the ambient air compressor 20a 'is controlled accordingly. In this way, by means of the controller 15, the inert gas rate provided by the inert gas system 20a, 20a 'can be determined.

The inert gas produced by the inert gas system 20a, 20a 'and / or the inert gas provided by the gas cylinder battery 20b is supplied to the space 10 to be monitored via the supply pipe system 17a; Of course, however, several shelters may be connected to the supply pipe system 17a. In detail, the supply of the inert gas provided with the inert gas source 20 is made via the outlet nozzles 17b, which are arranged at a suitable location in the space 10.

In the illustrated embodiment, inter alia, the inert gas, advantageously nitrogen, recovered locally from the ambient air. The inert gas generator or nitrogen generator 20a functions, for example, according to the known from the prior art membrane or PSA technology to produce nitrogen-enriched air with, for example, 90 vol .-% to 95 vol .-% nitrogen content. This nitrogen-enriched air serves as an inert gas, which is supplied to the space 10 via the supply pipe system 17a. The oxygen-enriched air resulting from the generation of the inert gas is discharged to the outside via another pipe system 13.

As already indicated, the inert gas source 20 is connected to the enclosed space 10 via the supply line system 17a and the discharge nozzle system 17b. The outlet nozzle system 17b preferably has a plurality of outlet nozzles, which are arranged distributed in the illustrated embodiment in a horizontal plane in the interior of the space 10. The regulated supply of the inert gas provided by the inert gas source 20 into the ambient air atmosphere of the enclosed space 10 takes place by suitable control of a control valve V1 in the supply line system 17a. In detail, the control valve V1 can be controlled correspondingly with the already mentioned control 15, so that the amount of the inert gas provided by the inert gas source 20 can be regulated correspondingly via the supply line system 17a and the outlet nozzle system 17b into the ambient air atmosphere of the enclosed space 10.

In the preferred embodiment, nitrogen is used as the inert gas, for example, which has a gas density of 1.251 kg / m ³ under normal conditions.

The outlet nozzle system 17b of the illustrated embodiment is designed such that it can be actuated by the controller 15 so that a transition layer consisting of a first gas layer A, a second gas layer B and an intermediate layer between the first and the second gas layer A, B is located in the enclosed space 10 without physical separation C forms existing gas stratification. In this gas stratification, the oxygen content in the zone of the first gas layer A substantially corresponds to the oxygen content of the ambient air atmosphere, the oxygen content in the zone of the second gas layer B corresponding to a specific, compared to the oxygen of the room air atmosphere, adjustable oxygen content. The determined oxygen content in the zone of the second gas layer B is adjusted by the amount of inert gas introduced into the zone of the second gas layer B via the supply line system 17a and the outlet nozzle system 17b.

In the illustrated embodiment, in order to achieve the most stable possible stratification in the room air atmosphere of the room, it is provided that the nitrogen used as inert gas is heated before being introduced into the enclosed space 10 compared to the mean temperature of the room air atmosphere of the room 10, consequently Specific density of the inert gas (nitrogen) is significantly lower compared to the specific density of the air present in the enclosed space before the introduction of the inert gas. Since the outlet nozzle system 17b is arranged in the upper area of the enclosed space 10 in the illustrated embodiment, first the upper area of the space 10 is flooded with the inert gas when introducing the preferably heated nitrogen into the enclosed space 10, while in the lower area of the room before the normal ambient air is present.

By stopping the inert gas supply before the entire volume of room air has been flooded with inert gas, the already heated two-layer gas layer can be formed in the enclosed space 10, the lower gas layer (first gas layer A) having an oxygen content corresponding to the oxygen content of the normal ambient air ( 21% by volume). On the other hand, by introducing the inert gas in the upper region of the space 10, there is formed a zone (second gas layer B) in which the oxygen content is reduced compared to the oxygen content of the normal ambient air or compared to the oxygen content of the first gas layer A.

Accordingly, in the zone of the second gas layer B, ie in the upper region of the space 10, there is a permanent inertization, so that in this zone the flammability of the goods stored there is reduced. The oxygen content in the zone of the second gas layer B is set to an inerting level which corresponds to a certain, compared to the oxygen content of the first gas layer A, oxygen content, said inerting can be determined by a suitable supply of inert gas in the zone of the second gas layer B accordingly is.

In the preferred embodiment of the inerting plant according to the invention, heated nitrogen is used as the inert gas. For this purpose, it would be conceivable for the inert gas source 20 to be followed by a corresponding heating system 18 in order to heat the inert gas supplied by the inert gas source 20 to the supply line system 17a. Alternatively or additionally, however, it would also be conceivable for the outlet nozzles 17b to be provided with corresponding heating elements in order to heat them accordingly when the inert gas is dispensed.

In order to ensure that the trained gas stratification is maintained over a longer period, the in Fig. 1 An inerting system 12 shown by way of example further comprises an exhaust system 12, which is arranged in the transition layer C lying between the first gas layer A and the second gas layer B. With this extraction system 12, the gas in the transition layer C is sucked off continuously or at events which can be defined by the controller 15, while fresh inert gas is simultaneously introduced into the zone of the second gas layer B via the outlet nozzle system 17b. With this measure, a mixing of the two gas layers A, B is effectively suppressed.

In detail, the exhaust system 12 has a suction nozzle system 12a arranged in the transition layer C and a fan 12b. The speed and / or the direction of rotation of the fan 12b can be controlled via the controller 15. Optionally, between the fan 12b and the suction nozzle system 12a, a control valve V2 controllable by the controller 15 can also be arranged. By means of a suitable regulation of the rotational speed of the fan 12b, a sufficient amount of gas is sucked out of the transition layer C via the suction nozzle system to maintain the gas stratification and discharged to the outside. On the other hand, can be changed by a suitable control of the fan 12b and its direction of rotation, so that if necessary with the suction 12th the transition layer C fresh air can be supplied.

By preferably the two formed in the enclosed space 10 gas layers A, B have different temperatures, a particularly stable gas stratification is achieved. This temperature difference can be maintained for a long time by suitable heating or cooling elements arranged in the space 10 or in the respective zones of the gas layers A, B. This (in Fig. 1 not explicitly shown) arranged in the respective zones of the gas layers A, B heating or cooling elements are preferably suitably controlled by the controller 15.

In the illustrated embodiment of the inerting according to the invention is advantageously provided that the suction 12 and in detail the Absaugdüsensystem 12a is made displaceable in the vertical direction, thus the layer thickness of the zone of the second gas layer B and in this context, the layer thickness of the zone Adjust first gas layer A as needed. It can be seen that in a case where the exhaust system 12 is located in the upper portion of the room 10, the zone of the second gas layer B becomes correspondingly thinner than when the exhaust system 12 is in the lower portion of the room 10.

In the preferred embodiment, the exhaust nozzle system 12a is located approximately in the center of the enclosed space 10, which is advantageous in that the lower portion of the space 10 in which the first gas layer A is formed is not affected by the introduced inert gas. so that, for example, a door 9, the free accessibility of the room 10 is possible.

However, the illustrated preferred embodiment of the inerting system is not only suitable as a preventive fire protection in the upper area of the room. Rather, in the illustrated embodiment, it is also possible to lower the room air atmosphere to a basic inerting level prior to forming the gas stratification by correspondingly lowering the oxygen content in the entire room 10, for example by introducing an inert gas relative to the oxygen content of the normal air. After the formation of the two gas layers A, B, the zone of the first gas layer A then has an oxygen content which is reduced compared to the normal ambient air, the zone of the second gas layer B containing an even further reduced oxygen content.

For this purpose, it is in principle conceivable that in addition to the already mentioned inert gas source 20 another (in Fig. 1 not shown) inert gas system is provided in order to make the space permanently before forming the gas stratification. However, the inert gas used here should have a specific gas density which is different from the gas density of the inert gas used for forming the gas stratification. It would be conceivable to use either different inert gases and / or inert gases with different temperatures.

Particularly preferably, a nozzle system 17b is used as the outlet nozzle system for continuously inerting the entire space, which is designed to distribute the introduced inert gas as uniformly as possible in the ambient air atmosphere. Of course, it is also conceivable to provide a corresponding air circulation in the space 10.

Moreover, it is advantageous if the system further comprises at least one oxygen measuring device 19 for detecting the oxygen content in the ambient air atmosphere of the enclosed space 10. In the in Fig. 1 In the embodiment shown, an oxygen measuring device 19 is provided both in the zone of the first gas layer A and in the zone of the second gas layer B. These oxygen measuring devices 19 are preferably designed as an aspirative system.

In order to achieve that the inerting system is suitable not only as a preventive fire protection, but also as a measure to combat a fire, it is provided that in the zone of the first gas layer A and in the zone of the second gas layer B continuously or at predetermined times or Events is measured on each one at least one fire parameter, wherein in the case of detection of at least one fire characteristic by preferably sudden introduction of inert gas into the zone of the second gas layer B, the oxygen content in this gas layer is lowered to a Vollinertisierungsniveau. Of course, it is also conceivable that in the zone of the first gas layer A, a detection of at least one fire characteristic is performed, and that in case of fire in the zone of the second gas layer B appropriate measures are provided.

In detail, the system is additionally equipped with a fire detection system 16 for detecting at least one fire parameter in the room air atmosphere of the enclosed space 10. The fire detection system 16 is preferably aspirative Executed system which takes the representative of the atmosphere of the first gas layer A on the one hand and the atmosphere of the second gas layer B on the other hand representative air or gas samples and a (in Fig. 1 not explicitly shown) for at least one fire characteristic feeds. The preferably continuously or at predetermined times or events emitted by the fire detection device 16 to the controller 15 signals from the controller 15 - optionally after further processing or evaluation of these - used, for example, to control the control valve V1 accordingly. In detail, the control 15 emits a corresponding signal for this purpose when a fire in the enclosed space 10 is detected by the fire detection device 16.

Fig. 2 shows a second preferred embodiment of the inerting plant according to the invention. This embodiment comprises as inert gas source 20 on the one hand an inert gas generator 20a, which is connected to an ambient air compressor 20a '. As with the reference to Fig. 1 described first embodiment, is controlled by the controller 15, the air flow rate of the ambient air compressor 20a ', according to set the inert gas provided by the inert gas system 20a, 20a' inert gas.

In addition to the inert gas system 20a, 20a 'is in the in Fig. 2 shown plant a gas cylinder battery or a pressure vessel 20 b provided in which liquefied CO ₂ is stored as an inert gas. The gas lavage battery 20b, which may of course also be embodied as a liquefied gas tank, is connected to the supply pipe system 17a via a 3-way valve V1 that can be controlled by the controller 15. The inert gas (nitrogen-enriched air) produced by the inert gas system 20a, 20a 'can be supplied to the enclosed space 10 via the supply pipe system 17a. Of course, it is also conceivable that the gas cylinder battery 20b is connected to the enclosed space 10 via a separate supply pipe system.

At the in Fig. 2 In the illustrated embodiment, two different inert gas types are used to form a gas stratification in the enclosed space 10. The first inert gas used here is the nitrogen-enriched air provided with the aid of the inert gas system 20a, 20a '. This nitrogen-enriched air is preferably used to set in the room air atmosphere of the enclosed space 10 a Dauerinertisierung at which the flammability of most stored in the space 10 goods is already significantly reduced. For this permanent inerting For example, a Grundinertisierungsniveau with an oxygen content of z. B. 15% by volume in question.

The basic inerting level permanently set in the room 10, for example, is monitored continuously or at predeterminable times or events with the aid of the controller 15 and the oxygen measuring device 19. If, for example, as a result of leaks in the enclosure of the enclosed space 10 or due to a (intentional or unwanted) air exchange after setting the Grundinertisierungsniveaus the oxygen content in the indoor atmosphere of the room 10 increases again, the controller 15 outputs a corresponding drive signal to the inert gas system 20a, 20a 'off. The inert gas system 20a, 20a 'then feeds nitrogen-enriched air into the piping system 17a. By suitable control of the 3-way valve V1, this nitrogen-enriched air fed into the pipeline system 17a is thus introduced into the space 10. The tracking of further nitrogen-enriched air takes place until it is detected via the oxygen measuring device 19 that the oxygen content in the ambient air atmosphere is lowered again to the desired basic inerting level.

A gas stratification with different oxygen contents is at the in Fig. 2 illustrated embodiment, by the stored in the gas battery door 20b CO _{2 is} preferably introduced into the lower region of the space 10. In the preferred embodiment, the CO _{2 is introduced} into the space 10 after an inerting level (e.g., a baseline or full inertization level) has already been set by the previously described introduction of nitrogen-enriched air.

For the formation of the gas stratification, the controller 15 controls the control valve V1 arranged in the supply line system 17a accordingly. Since (gaseous) CO _{2 has} a density of 1.977 kg / m ³ and is thus significantly heavier than, for example, normal air and heavier than nitrogen, a so-called "CO ₂ - forms when CO _{2 is introduced} into the lower area of the enclosed space 10. See ", ie a gas stratification B in the lower part of the room 10, in which there is an increased concentration of CO ₂ and thus in comparison to the oxygen content in the upper region of the room (layer A) further reduced oxygen concentration. The CO ₂ can be supplied to the space 10 either in gaseous or in liquid form.

In the space 10, a gas stratification is thus formed, which consists of a formed in the upper part of the space 10 gas layer A and formed in the lower part of the space gas layer B. In the formed in the upper part of the space 10 gas layer A, an oxygen content is present, which substantially corresponds to the set before initiation of the CO ₂ gas Grundinertisierungsniveau. In the formed in the lower part of the space 10 gas layer B, the introduced CO ₂ gas is contained and thus has a compared to the gas layer A further reduced oxygen content.

Between the two gas layers A and B, a transition layer C is formed as a result of mixing operations. At the in Fig. 2 However, this transition layer C should be relatively thin, since the difference between the average density of the gas contained in the layer A and the average density of the gas contained in the layer B is relatively large, and thus the mixing primarily only by the diffusion current the gas particle is conditional.

It can be seen that when referring to Fig. 2 described second preferred embodiment of the present invention particularly flammable goods or goods which outgas over time flammable substances (eg hydrocarbons), are preferably stored in the lower gas layer B, while stored goods with a normal inflammatory behavior in the upper gas layer A. can be.

The gas stratification should be stopped if a fire has broken out or is about to break out in the room air atmosphere of the enclosed space. For this purpose, different fire detection systems 16 are preferably provided in the enclosed space 10.

The invention is not limited to the embodiments of the inerting system shown in the drawings. Rather, all advantages and further developments, as generally described and stated in the patent claims, are considered to belong to the invention.

In particular, the solution according to the invention is not restricted to the use of nitrogen as an inert gas. Also, the inert gas used must not be appropriately tempered before being introduced into the enclosed space.

Claims (16)

1. An inerting method for reducing the risk of the outbreak of fire in an enclosed space (10), wherein the method comprises introducing into the enclosed space (10) at least one inert gas or an inert gas mixture having a different gas density (ρ _gas ) from the mean gas density (ρ_gas ) of the ambient atmosphere of the enclosed space (10), in such a way that a gas stratification composed of a first gas layer (A), a second gas layer (B), and a transition layer (C) situated between the first and second gas layers (A, B) is formed and maintained in the enclosed space (10) without any structural separation, wherein the oxygen content in the first gas layer (A) corresponds substantially to the oxygen content of the ambient atmosphere, and wherein the oxygen content in the second gas layer (B) corresponds to a specific, settable oxygen content which is lower than the oxygen content of the ambient atmosphere.
2. The method according to Claim 1, wherein
   the gas stratification formed in the enclosed space (10) is maintained by the regulated feeding of the inert gas or the inert gas mixture into the second gas layer (B), and by the appropriate extracting of gas from the second gas layer (B) and/or from the transition layer (C).
3. The method according to Claim 1 or 2, wherein
   the temperature of the first gas layer (A) and the temperature of the second gas layer (B) are measured, and wherein the gas stratification formed in the enclosed space (10) is maintained by setting and maintaining a specific temperature difference between the temperature of the first gas layer (A) and the temperature of the second gas layer (B).
4. The method according to any one of the preceding claims, wherein
   the oxygen content in the second gas layer (B) is measured continuously or at predefined times or upon predefined events, and wherein the oxygen content in the second gas layer (B) is maintained at the inertization level corresponding to the defined oxygen content by the regulated feeding of inert gas or an inert gas mixture as well as the regulated extracting of gas from the second gas layer (B) and/or from the transition layer (C).
5. The method according to any one of the preceding claims, wherein
   the inert gas or inert gas mixture has a specific gas density (ρ_gas ) which differs from the specific gas density (ρ _gas ) of the ambient atmosphere at the same temperature.
6. The method according to any one of the preceding claims, wherein
   when the inert gas or inert gas mixture is introduced, the inert gas or inert gas mixture has a temperature which differs from the mean temperature of the ambient atmosphere.
7. The method according to any one of the preceding claims, wherein
   prior to the gas stratification being formed in the enclosed space (10), by the introduction of an inert gas or an inert gas mixture the ambient atmosphere of the enclosed space (10) is changed in such a way that the oxygen content in the ambient atmosphere is lowered to a specific base inertization level which corresponds to a lower oxygen content compared to the normal air oxygen content.
8. The method according to Claim 7, wherein
   the oxygen content in the first gas layer (A) is measured continuously or at predefined times or upon predefined events, and wherein the oxygen content in the first gas layer (A) is maintained at the base inertization level by the regulated feeding of inert gas or an inert gas mixture into the first gas layer (A) as well as the regulated extracting of gas from the first gas layer (A) and/or from the transition layer (C).
9. The method according to any one of the preceding claims, wherein
   at least one fire characteristic is measured in the second gas layer (B) continuously or at predefined times or upon predefined events, and wherein in the event that a fire is detected, the oxygen content in the second gas layer (B) is lowered to a full inertization level, which corresponds to a further reduced oxygen content compared to the defined inertization level, by the sudden introduction of inert gas or an inert gas mixture into the second gas layer (B).
10. The method according to any one of the preceding claims, wherein
    at least one fire characteristic is measured in the first gas layer (A) continuously or at predefined times or upon predefined events, and wherein in the event that a fire is detected, the oxygen content in the first gas layer (A) is lowered to an inertization level, which corresponds to a reduced oxygen content compared to the oxygen content of the ambient atmosphere, by the sudden introduction of inert gas or an inert gas mixture into the first gas layer (A).
11. The method according to any one of the preceding claims, wherein the respective layer thicknesses are adjustable.
12. A device for reducing the risk of a fire in an enclosed space (10) and for carrying out the method according to any one of Claims 1 through 11, wherein the device comprises at least one inert gas source (20) for supplying an inert gas or an inert gas mixture having a gas density (ρ_Gas ) which differs from the mean gas density (ρ_Gas ) of the ambient atmosphere of the enclosed space (10), and a supply and outlet nozzle system (17a, 17b), which is controllable by a control unit (15), for introducing the inert gas or inert gas mixture supplied by the inert gas source (20) into the enclosed space (10), wherein the supply and outlet nozzle system (17a, 17b) is designed in such a way that a gas stratification composed of a first gas layer (A), a second gas layer (B), and a transition layer (C) situated between the first and second gas layers (A, B) is formed and maintained in the enclosed space (10) without any structural separation, wherein the oxygen content in the first gas layer (A) corresponds substantially to the oxygen content of the ambient atmosphere, and wherein the oxygen content in the second gas layer (B) corresponds to a specific, settable oxygen content which is lower than the oxygen content of the ambient atmosphere.
13. The device according to Claim 12, wherein
    the outlet nozzle system (17b) has at least one vertically displaceable outlet nozzle.
14. The device according to Claim 12 or 13, further comprising a suction system (12), which is controllable by a control unit (15), in order to extract gas from the first gas layer (A) and/or the second gas layer (B) and/or the transition layer (C) in a regulated manner.
15. The device according to Claim 14, wherein
    the suction system (12) has at least one vertically displaceable exhaust nozzle (12a).
16. The device according to any one of Claims 12 through 15, further comprising a mechanism (18) for regulating the temperature in the first gas layer (A) and/or the temperature in the second gas layer (B).

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