EP0804945A2 - Method and device for extinguishing fires in an enclosed space - Google Patents

Abstract

The method involves pre-cooled combustion products introduced into room until an atmosphere exists which prevents burning. The combustion products before cooling are completely oxidised using atmospheric air. They are cooled with the aid of a liquid medium from an available cooling system, e.g. a road vehicle or a ship diesel engine. The extinguishing device comprises a housing (1) in which is a combustion chamber (14) containing an aerosol-producing charge of solid fuel (5), an ignition device (3) for igniting the charge and at least one outlet nozzle (2), connected to the combustion chamber. The housing is divided by a cross-running intermediate wall (11) with at least one opening (15). To the at least one wall opening is fitted a mixture tube (8) coaxial to the outlet nozzle, which with its end turned away from the intermediate wall issues into the atmosphere.

Description

The invention relates to fire extinguishing technology, in particular the prevention and extinguishing of fires in closed rooms.

To extinguish a fire in a closed room, it is known to create an atmosphere in the room that prevents combustion. Inert solvents (carbon dioxide, nitrogen, argon, water vapor), volatile inhibitors, halogen-containing agents or extinguishing powder (A.N. Baratov, E.M. Ivanov, "Extinguishing Fires in the Chemical and Petroleum Processing Industry", Moscow, Chemistry, 1979) are used as fire extinguishing agents.

However, the known fire extinguishing methods for room fires cannot be used to extinguish alkali and alkaline earth metals as well as some metal hydrides and compounds that contain oxygen in their molecules.

The construction of fire extinguishing systems for rooms of very large buildings is difficult because a sufficient amount of gas has to be provided in a certain time. In addition, because of the risk of suffocation, signaling systems are necessary that indicate the use of the extinguishing process.

Deleting with halogen-containing compounds also has a number of disadvantages. These agents can have a toxic effect on humans, because when they are extinguished, their thermal decomposition forms products with a high degree of corrosion.

In addition, rooms that are particularly at risk of fire are usually protected with very large fire extinguishing systems for rooms in which halogenated hydrocarbons are used. Due to the international measures to protect the ozone layer in accordance with the Montreal Protocol (1987), the fluorocarbons must be reduced by half by 1995 and completely abandoned by 2000 because these substances have a high ozone-depleting potential.

Fire extinguishing systems with devices for producing fluorocarbon compounds are already known, for example from GB-PS 2 020 971. The disadvantage of these systems is the harmful effect of the fluorocarbon compounds on the environment. In addition, these systems are of fairly large dimensions and weight, so that they cannot be used very effectively to extinguish fires in means of transport, for example in air traffic.

From GB-PS 2 028 127 a fire extinguishing device with a housing having an outlet opening, a charge for producing the fire-extinguishing substance and an ignition unit is known. When the ignition unit is actuated, the pyrotechnic or solid fuel charge ignites, the gaseous combustion products of which form the fire-extinguishing substance that enters the fire area through the outlet opening and extinguishes the fire. However, this device has insufficient effectiveness because the extinguishing capacity of the gaseous combustion products, which are inert solvents, is low.

PCT / RU 92/00071 discloses a method for producing a fire-extinguishing mixture, in which a mixture of solid particles and inert gases is formed when the charge consisting of a pyrotechnic composition is burned off becomes. The high degree of dispersion of these particles, their chemical properties and the freshly formed surface ensure a considerable fire-extinguishing effect.

However, this method has a number of disadvantages. The high temperature of the combustion products leads to an increase in the average temperature in the room to be protected, which has a detrimental effect on the living beings and valuables (eg documents, paintings, etc.) in this room. As the aerosol cools, the proportion of the unreacted elements in the combustion products and consequently also the proportion of NH ₃ , CO, nitrogen oxide and other products in the fire extinguishing agent increases dramatically. In addition, when the pyrotechnic, aerosol-forming fire-extinguishing mixture and ballistic compositions consisting of solid fuel are burned, gaseous products of incomplete combustion of the organic components (NH ₃ , H ₂ , CHx) and nitrogen oxides (NOx) are released in addition to the primary gaseous aerosol products with extinguishing action, which pollutes the environment with these products.

The invention is based on the object of developing a method and a device for extinguishing room fires, by means of which an environmentally friendly and fire-preventing medium can be formed and introduced into the space to be protected which is not harmful to health.

This object is achieved by a method according to claim 1 and an apparatus according to claim 4.

In the method according to the invention and the device according to the invention, the extinguishing takes place through the inhibiting effect of the condensed aerosol phase on the flames. The aerosol phase is formed when the solid fuel is burned after ignition of a charge consisting of a pyrotechnic composition, the combustion products first being post-burned by means of the oxygen-containing oxidizing agent, for example the air, and then being cooled to the required temperature.

$${\text{2NH}}_{\text{3}}{\text{+ 1,5O}}_{\text{2}}{\text{→N}}_{\text{2}}{\text{+ 3H}}_{\text{2}}\text{O;}$$

$${\text{2H}}_{\text{2}}{\text{+ O}}_{\text{2}}{\text{→ 2H}}_{\text{2}}\text{O;}$$

$${\text{CHx + O}}_{\text{2}}{\text{→ CO}}_{\text{2}}{\text{+ H}}_{\text{2}}\text{O)}$$

sowie die Neutralisierung der Stickstoffoxide $${\text{(NOx + CO → N}}_{\text{2}}{\text{+ CO}}_{\text{2}}\text{;}$$

$${\text{NOx + NH}}_{\text{3}}{\text{→ N}}_{\text{2}}{\text{+ H}}_{\text{2}}\text{O;}$$

$${\text{NOx + H}}_{\text{2}}{\text{→ N}}_{\text{2}}{\text{+ H}}_{\text{2}}\text{O;}$$

$${\text{NOx + CHx →N}}_{\text{2}}{\text{+ H}}_{\text{2}}{\text{O + CO}}_{\text{2}}\text{)}$$

erfolgt vorzugsweise in einem Ejektorstrahl.The afterburning of the products of incomplete combustion until they are completely oxidized by atmospheric oxygen $${\text{(2CO + O}}_{\text{2nd}}{\text{→ 2CO}}_{\text{2nd}}\text{;}$$

$${\text{2NH}}_{\text{3rd}}{\text{+ 1.5O}}_{\text{2nd}}{\text{→ N}}_{\text{2nd}}{\text{+ 3H}}_{\text{2nd}}\text{O;}$$

$${\text{2H}}_{\text{2nd}}{\text{+ O}}_{\text{2nd}}{\text{→ 2H}}_{\text{2nd}}\text{O;}$$

$${\text{CHx + O}}_{\text{2nd}}{\text{→ CO}}_{\text{2nd}}{\text{+ H}}_{\text{2nd}}\text{O)}$$

and the neutralization of nitrogen oxides $${\text{(NOx + CO → N}}_{\text{2nd}}{\text{+ CO}}_{\text{2nd}}\text{;}$$

$${\text{NOx + NH}}_{\text{3rd}}{\text{→ N}}_{\text{2nd}}{\text{+ H}}_{\text{2nd}}\text{O;}$$

$${\text{NOx + H}}_{\text{2nd}}{\text{→ N}}_{\text{2nd}}{\text{+ H}}_{\text{2nd}}\text{O;}$$

$${\text{NOx + CHx → N}}_{\text{2nd}}{\text{+ H}}_{\text{2nd}}{\text{O + CO}}_{\text{2nd}}\text{)}$$

preferably takes place in an ejector jet.

The afterburning and the subsequent cooling of the combustion products of the aerosol-forming fire-extinguishing compositions can increase the effectiveness of the fire-extinguishing aerosol and operational safety, since the combustion products contain no life-threatening gases.

An embodiment of the invention is explained in more detail with reference to the accompanying drawing, which shows a longitudinal section of a device for extinguishing room fires.

The device for extinguishing room fires consists of a cylindrical housing 1, in which a combustion chamber 14 is formed adjacent to an end face. In the combustion chamber 14, a charge 5 of a solid fuel is arranged at the front end, which charge can be, for example, an aerosol-forming agent which contains a nitrate of an alkaline earth metal, an organic combustible binder and an aerosol gas generator, whereby it is an alkaline earth nitrate, potassium nitrate with a specific metallic surface of not less than 1500 cm ² / g, as a combustible binder, phenol formaldehyde resin with an average particle diameter of not more than 100 μm, and as aerosol gas generator, dicyandiamide with a particle size of not more than 15 μm.

• Kaliumnitrat 67-72
• Phenolformaldehydharz 8-12
• Dicyandiamid Rest

The constituents are preferably contained in the following ratio in mass%:

• Potassium nitrate 67-72
• Phenol formaldehyde resin 8-12
• Dicyandiamide residue

An ignition unit 3 for igniting the charge 5 is also provided in the combustion chamber 14. On the side of the combustion chamber 14 facing away from the charge 5, an outlet nozzle 2 in the manner of a Venturi nozzle is applied centrally, which opens into the combustion chamber 14 and, after the constriction, has a jet pipe section 6.

In the outer wall of the housing 1 at the level of the jet pipe section 6, inlet openings 9 are provided for the supply of air to the jet pipe section 6.

At a distance from the combustion chamber 14, an intermediate wall 11 is arranged transversely to the longitudinal direction of the housing 1. A central wall opening 15 is provided in the intermediate wall 11, from which a mixing tube 8 extends coaxially to the housing 1 to the other end face 16 of the housing 1 and opens into the open at this.

The free end of the jet pipe section 6 extends through the opening 15 coaxially into the mixing pipe 8. A swirling device 10 is arranged in the annular gap between the beam pipe section 6 and the mixing pipe 8.

The annular cooling space 7 between the mixing tube 8, the intermediate wall 11, the other end face 16 and the wall of the housing 1 is closed. On the wall of the housing 1, an inlet connector 12 and an outlet connector 13 are provided, which are connected to the annular cooling space 7.

The cooling space is connected to a cooling system via the inlet connection 12 and the outlet connection 13, e.g. from a motor vehicle or a marine engine, connected and filled with a coolant.

To extinguish a fire, the ignition device 3 is triggered, whereby the charge 5 is ignited. The resulting combustion products emerge from the combustion chamber 14 due to the explosion pressure through the outlet nozzle 2 and the jet pipe section 6 and are blown into the air in the mixing pipe 8 at the free end of the jet pipe section 6 and mix with it.

In the mixing tube 8, the combustion products are afterburned by means of the air until they are completely oxidized and then cooled to the required temperature.

In the fire extinguishing device described only one mixing tube 8 is provided. Depending on the requirements for the outlet temperature of the aerosol and the length of the aerosol jet, however, a plurality of mixing tubes 8 can be provided in parallel, into each of which a jet tube section 6 of an outlet nozzle 2 extends, which is connected to the combustion chamber 14. This divides a large jet into several thinner jets, which results in better cooling and better mixing with the air, and consequently more effective afterburning of the unreacted combustion products. The non-contact Cooling the aerosol eliminates "contamination" of the aerosol by the decomposition products of the coolant and is therefore extremely environmentally friendly.

Both ambient air and any other gaseous oxidant can be used as the oxidizing agent.

The air can be supplied under pressure to improve the air supply and to extend the aerosol jet. However, operation without increased pressure is also possible.

Claims (6)

Method for extinguishing room fires, in which pre-cooled combustion products are introduced into a room until there is an atmosphere in the room which prevents combustion, characterized in that the combustion products are completely oxidized before cooling with the aid of an oxygen-containing oxidizing agent. A method according to claim 1, characterized in that ambient air is used as the oxygen-containing oxidizing agent. Method according to claim 1 or 2, characterized in that the combustion products are cooled with the aid of a liquid coolant from an existing cooling system, for example a motor vehicle or a marine diesel engine. Device for extinguishing room fires, comprising a housing (1), a combustion chamber (14) arranged in the housing (1), an aerosol-generating charge (5) made of solid fuel in the combustion chamber (14), an ignition device (3) for igniting the charge (5) and at least one outlet nozzle (2) which is connected to the combustion chamber (14), characterized in that - the housing (1) is divided by a transverse partition (11) with at least one wall opening (15), a mixing tube (8) is attached to the at least one wall opening (15) coaxially to the outlet nozzle (2) and opens into the atmosphere with its end facing away from the intermediate wall (11), - The space (7) between the mixing tube (8) and the inner wall of the housing (1) is filled with a coolant, - In the wall of the housing (1) between the intermediate wall (11) and the end wall of the combustion chamber (14) facing the end face of the combustion chamber (14) inlet openings (9) are formed and - The outlet nozzle (2) is designed in the form of a jet pipe (6) and extends through the wall opening (15) into the mixing tube (8), a gap being present between the jet tube (6) and the mixing tube (8). Device according to claim 4, characterized in that a swirling device (10) is arranged in the gap between the jet pipe (6) and the mixing pipe (8). Apparatus according to claim 4 or 5, characterized in that two sockets (12, 13) are arranged on the housing in the region of the closed space (7) filled with the coolant and can be connected to a cooling system.

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