RU2740461C2 - Aerosol-forming, fire-extinguishing composition based on saccharides - Google Patents

Abstract

FIELD: fire-prevention equipment.

SUBSTANCE: invention relates to volumetric aerosol fire-fighting, in particular, to solid-fuel aerosol-forming compositions (AFC). Technical result is achieved by the fact that aerosol-forming composition based on saccharides contains combustible-binding sorbitol, gas generator dicyandiamide, potassium nitrate oxidant, according to invention additionally added are technological additives ceresin or metal stearate, iron oxide catalyst. Components included in the AFC are taken in the following ratios, wt %: sorbitol 15÷40, dicyandiamide 2÷5, iron oxide 0.1÷5, ceresin or metal stearate 0.1÷5, potassium nitrate—balance.

EFFECT: technical result is to increase fire extinguishing efficiency AFC (less 0_030 g/m³) at a low calorific value fuel and a binder, and a relatively high oxygen content in the molecular link, which enables to reduce combustion temperature in combination with optimum speed, which is ensured by small distance between particles reacting (comparable to size of molecules).

5 cl, 2 tbl

Description

The invention relates to volumetric aerosol fire extinguishing, in particular to solid propellant aerosol-forming compositions (AOC).

Most aerosol formulations have a relatively high combustion product temperature, i.e. emitted fire extinguishing aerosol, close to 1000 ° C, with acceptable fire extinguishing efficiency, and close to the maximum permissible content of toxic gaseous combustion products such as carbon monoxide (CO), nitrogen oxides (NO, NO ₂ ) and ammonia (NH ₃ ).

These parameters are primarily due to the use in AOC of high-calorific fuels and combustible binders from a number of hydrocarbon compounds (phenol-formaldehyde, epoxy, polyester resins, etc.), as well as technical carbon (coal, soot). Typical AOS of a similar series are the compositions presented by RF patents for inventions №2046614, №2006239, №2146546, №2477163, №2477162.

The thermal-physical characteristics of some types of fuel in AOC are presented in Table 1.

Combustion in air of AOC with a high-calorific fuel or a combustible binder from a number of hydrocarbon compounds is accompanied by intense glow of hot gases and incandescent particles, which have a significant thermal effect on the environment.

This makes it difficult to use AOS in fire-extinguishing aerosol (GOA) generators without a cooler, in sealed and conditionally sealed volumes and excludes their use in portable generators (GOAP) designed to suppress the flame combustion of objects (for example, clothing on a person) in an open space.

In contrast to these compositions, the saccharide-based aerosol-forming composition proposed by the authors is environmentally friendly, low-temperature, low-flame.

Saccharides, their modifications and mixtures in fire extinguishing techniques have been known for a long time, mainly as emulsifiers, for creating high expansion foams.

From the prior art known "Fire extinguishing composition containing a saccharide and a saccharide derivative" (patent US 9662522 B2), which uses saccharides and their derivatives, but not to generate an aerosol-gas mixture, but to improve the fire extinguishing properties of GOA, equipped with a conventional pyrotechnic charge AOC ... The aerosol generated by this charge throws the saccharide mixture into the fire zone. That is, saccharides are used essentially as a powder fire extinguishing agent.

The closest analogue to the proposed technical solution (prototype) is "Aerosol-forming solid propellant composition for extinguishing a fire" (patent UA 7773), containing wood flour and potassium nitrate. Additionally, it contains potassium perchlorate, sucrose or lactose, or sorbitol, dicyandiamide or diphenylamine, with the following ratio of components, wt. %: potassium perchlorate 5 ÷ 8; potassium nitrate 50 ÷ 63; sucrose, lactose or sorbitol 20 ÷ 33; dicyandiamide or diphenylamine 5 ÷ 10; wood flour - the rest.

The disadvantages of the prototype include:

- increased content of dicyandiamide, which disturbs the balance of solid and gaseous components of the gas-aerosol complex, which reduces the fire extinguishing efficiency. In addition, the conditions for the ignition of the composition worsen;

- the presence of potassium perchlorate in the composition, which, as shown by many years of experience, is undesirable in compositions with sorbitol, primarily due to the ability of chlorine salts to slow down its crystallization. The composition may not harden for months and has cold flow. In addition, potassium perchlorate is a component of increased danger - it is sensitive to friction, requires special storage conditions and is limited in implementation;

- the use of wood flour as part of the prototype increases the calorific value of AOC, (i.e., to an increase in the temperature of the gas-aerosol mixture) and increases the content of harmful substances (mainly carcinogens) in the generated gas-aerosol cloud;

- the permissible replacement of dicyandiamide with diphenylamine in the indicated amount leads to a significant decrease in the operating temperature of the AOC (the melting point of diphenylamine is 56 ° C);

- the absence of catalysts in the composition, providing stable combustion with an optimal rate and a minimum content of carbon monoxide;

- absence in the composition of additives - stabilizers, antioxidants, without which AOS containing sorbitol degrades in a short period of time.

For clarity, significant differences are shown in Table 2.

It should be noted that the two variants of the prototype production also contain a number of serious shortcomings. We offer a brief overview of these technologies:

Option 1 - the initial components are crushed, mixed in appropriate proportions and pressed. To obtain compositions with the declared properties, it is necessary to grind the components to fractions of 20-50 microns. In this case, even such an inert component as dicyandiamide becomes explosive in an air-dust cloud, not to mention the fact that ground potassium perchlorate may be present there at the same time. The pressing process is also dangerous. the pressing pressure of the dry mixture is not less than 2500 kg / cm ² , at the melting temperature of the binder (186 ° C for sucrose).

Option 2 - the initial components are dissolved in water, the solution is evaporated to the required conditions, then poured into molds and dried. The technology is much safer, but it requires special equipment: vacuum equipment, drying ovens, powerful ventilation and an increased production area. The process requires high electrical power and is lengthy (only drying can take more than 30 hours).

The problem to be solved by the proposed invention is to create a family of AOS, devoid of these disadvantages.

The technical result achieved when solving this problem is to increase the fire extinguishing efficiency of AOC (less than 0.030 g / m ³ ) and reduce the temperature of the generated gas-aerosol jet (less than 100 ° C). This result is provided by two main factors:

- the use of a combustible binder with a low calorific value and a relatively high oxygen content in the molecular unit;

- the use of melt technology, which makes it possible to reduce the distance between the particles of the AOS components to a size comparable to the size of the molecules.

The basic composition of the proposed AOS family, based on saccharides, contains a combustible binder - sorbitol, a gas former - dicyandiamide, an oxidizing agent - potassium nitrate, additionally technological additives are introduced - ceresin or a metal stearate, for example sodium, a catalyst - for example, iron oxide and a stabilizer of chemical resistance - for example , centralite and / or diphenylamine in an amount not exceeding 0.5 wt. %.

The components included in the AOS are taken in the following ratios wt. %: sorbitol - 15 ÷ 40, dicyandiamide - 2 ÷ 5, iron oxide - 0.1 ÷ 5, ceresin or copper stearate 0.1 ÷ 1.0, centralite and / or diphenylamine in an amount not exceeding 0.5 wt. % - 0.1 ÷ 1.0, potassium nitrate - the rest.

The optimal amount of dicyandiamide, in combination with a catalyst, allows for stable combustion and an optimal combustion rate of the composition of 1.9-2.2 mm / s. It is obvious that an increase in the amount of dicyandiamide in the proposed AOC will lead to a decrease in the rate of the combustion reaction and worsen the flammability.

Iron oxide included in the composition acts as a catalyst, accelerating the reaction.

Along with the gasifier dicyandiamide, urotropine, melem, guanidine, melon, melamine, organic metal salts can also be used.

Chemical compounds of metals or their mixture can act as catalysts, and metal nitrates or their mixture can act as an oxidizing agent.

In a preferred embodiment of the invention, sorbitol is used as a combustible binder in a mixture with a monosaccharide, for example glucose.

In a further preferred embodiment of the invention, sorbitol is used as a combustible binder in a mixture with an oligosaccharide, for example sucrose.

In a further preferred embodiment, sorbitol is used as the combustible binder mixed with a polysaccharide, for example starch.

In another embodiment of the invention, nitrocellulose in various variations is used as a combustible binder.

In a further preferred embodiment, urotropine is used as a blowing agent in a mixture with dicyandiamide.

In a further preferred embodiment, an organic metal salt is used as a blowing agent.

It should be especially noted the efficiency of using the proposed low-flame AOS based on saccharides in portable generators (GOAP), without a cooler, designed to suppress the flame combustion of objects (for example, clothing on a person) in an open space.

The temperature of the gas-aerosol jet of these fire extinguishers does not exceed 50 ° C at a distance of 20 cm from the outlet.

The proposed AOS can be used as a displacing agent in powder and liquid fire extinguishing systems, enhancing the fire extinguishing effect.

As noted earlier, the technology for manufacturing low-flame AOS based on saccharides is simple and safe. The components are melted in a conventional reactor with a stirrer at a temperature of about 100 ° C (the melting point of sorbitol, the main component of the combustible binder is 95 ° C), that is, at a temperature well below the ignition temperature of the components of the composition.

Then the composition is poured into molds or cartridges and immediately after cooling (40-60 minutes) can be used for its intended purpose. This technology, using the uniform distribution of the crushed components in the melt of the combustible-binder, provides a distance between the particles that react, comparable to the size of the molecules. This circumstance, along with a well-chosen chemical composition, gives unique performance properties to the AOC proposed by the authors.

If necessary, the proposed AOC can be manufactured using traditional technologies: extrusion, rolling, blind and continuous pressing, etc., but it should be taken into account that the performance characteristics of AOC deteriorate.

We emphasize: the effectiveness of the proposed AOS family is determined by the distance between the particles entering into the reaction, which is comparable to the size of molecules and a well-formed recipe.

Claims (6)

An aerosol-forming fire-extinguishing composition based on saccharides, containing a combustible and oxidizing agent - potassium nitrate, characterized in that the distance between the particles that react is comparable to the size of molecules, and the composition contains: combustible - sorbitol or sorbitol mixed with monosaccharides or sorbitol in a mixture with oligosaccharides or sorbitol in a mixture with polysaccharides, a blowing agent, technological additives, a catalyst - iron oxide, while the components are taken in the following ratios, wt%: Combustible 15 ÷ 40 Gasifier 2 ÷ 5 Catalyst 0.1 ÷ 1.0 Technological additives 0.1 ÷ 5.0 Oxidizer rest 2. The composition according to claim 1, characterized in that it contains dicyandiamide as a blowing agent. 3. Composition according to claim 1, characterized in that it contains urotropine mixed with dicyandiamide as a blowing agent. 4. A composition according to claim 1, characterized in that it contains organic metal salts as a blowing agent. 5. The composition according to claim 1, characterized in that it contains melem or melamine as a blowing agent.