RU2510754C2 - Fire-extinguishing solution and method for fire fighting with this solution - Google Patents

Abstract

FIELD: fire-fighting equipment.

SUBSTANCE: invention relates to fire-fighting and can be used to extinguish fires primarily of Class A (solid combustible substances and materials), as well as forest and peat fires. The fire-extinguishing solution is prepared on the basis of the buffer solution containing borates and/or phosphates, and also calcium carbonates and/or magnesium carbonates.

EFFECT: invention provides increased fire-extinguishing efficiency.

8 cl

Description

The present invention relates to fire fighting and can be used to extinguish class A fires (solid combustible substances and materials), as well as forest and peat fires.

Currently, various foaming agents and surfactants are used to extinguish litter-humus and peat fires (NP-1, OP-7, OP-10, nekal, solutions of humic substances contained in peat and solutions of ammonia alkali extracted from it) . Long-term practice of their application has shown that peat treated with solutions of borates, phosphate-ammonium salts, sodium alginate and foam with the addition of diammonium phosphate or sodium alginate is the most fire-resistant. However, most of these preparations are effective only for extinguishing peat massifs when fed by ground or creating wet barrier bands, in addition, these extinguishing agents have a small chemical fire extinguishing capacity and are effective only for a short time (before rain).

Known compositions based on water with additives for various purposes to extinguish fires.

For example, in RF patent No. 2209645 an extinguishing composition is described which contains halogenated hydrocarbons - ethyl bromide, stabilizers - tall pitch and ammonium hydroxide in the following ratio of components: ethyl bromide 10-20 wt.%, Tall pitch 0.1-0.2 wt. %, ammonium hydroxide 0.45-1.0 wt.%, water - the rest.

The disadvantage of this composition is the small fire extinguishing capacity and low efficiency.

In the patent of the Russian Federation No. 2310421 a method for extinguishing a fire by supplying water saturated with carbon dioxide to the fire site is described. Water is saturated to a mass gas concentration of 2 ÷ 6%, after which the gas-liquid mixture is frozen to a temperature of -15 ÷ -20 ° C, forming briquettes weighing 4 ÷ 12 kg, which cover the fire. This method is very difficult to use and not effective enough.

The closest set of essential features to the proposed is a fire extinguishing solution according to the patent of the Russian Federation No. 2262367.

Known solution contains ground clay, ground asbestos, sodium chloride and water. The combination of components in a certain ratio provides an effective, inexpensive and easy-to-use aqueous composition.

The disadvantages of the known composition are:

- insufficient fire extinguishing effectiveness in extinguishing forest and peat fires;

- the ability to supply only by dumping (discharge);

- the inability to suppress the smoldering foci of burning forest litter and especially peat massifs;

- due to the fractional composition and structure of the fire extinguishing solution, the impossibility of its use in backpack fire extinguishing installations;

- the difficulty of obtaining the finished solution (requires a mechanized method of preparation).

The problem to be solved in this invention is to increase fire extinguishing efficiency, versatility in the methods of supplying the fire to the fire and the cost-effectiveness of the fire extinguishing solution and the method of extinguishing a fire using it.

To this end, it is proposed to prepare a fire extinguishing solution based on salts of boric and / or phosphoric acid, as well as calcium and / or magnesium carbonates in pure form or in the form of rocks or industrial waste containing them, moreover, the pH of the solution is 6.5-10, 3.

The phlegmatizing and insulating effect of these substances is achieved due to the fact that, as a result of physicochemical processes, carbon dioxide is released. In addition, when the proposed fire extinguishing solution gets on the surface, a strong nanoscale protective layer is formed, consisting of boron and calcium oxide compounds, which can only be destroyed mechanically.

Also, chemical inhibition of the combustion reaction occurs due to the fact that a large amount of energy is spent on the destruction of intermolecular bonds of calcium and / or magnesium carbonates during their thermal decomposition.

Additional differences of the fire extinguishing solution we offer are:

- preferably, the pH of the solution is 9-9.5;

- in one embodiment, the fire extinguishing solution contains water 1 m ³ , sodium tetraborate 10.1 kg, calcium carbonate 1.6 kg;

In the proposed method of extinguishing a fire, including spraying a fire extinguishing solution over a fire, it is proposed to use a solution containing salts of boric and / or phosphoric acid, as well as calcium and / or magnesium carbonates in pure form or in the form of rocks or industrial wastes containing them moreover, the pH of the solution is in the range from 6.5 to 10.3.

Additional differences of the method are:

- preferably, the pH of the solution is in the range of 9-9.5;

- in one embodiment, the fire extinguishing solution contains water 1 m ³ , sodium tetraborate 10.1 kg, calcium carbonate 1.6 kg;

- serves a fire extinguishing solution in the fire by spraying with the help of specialized aircraft;

- a fire extinguishing solution is supplied to the fire by discharge or discharge using specialized aircraft.

The proposed fire extinguishing solution and method of its application have the following advantages:

- high dilution ability, since the evaporation of water produces a large amount of steam and non-combustible gases generated during the decomposition of substances that make up the solution;

- chemical neutrality in relation to building, structural, finishing and other materials;

- universality in supply methods and the possibility of application for extinguishing fires of most classes, especially class A and B fires;

- environmental safety, since during the quenching process no ecosystem poisons are formed, only calcium and / or sodium carbonates remain, which are rock-forming salts.

The essence of the invention is as follows. Water is taken as the basis of the buffer solution. To increase fire extinguishing efficiency, it is subjected to chemical modification, namely, a buffer solution is created using, for example, sodium tetraborate (borax) to shift the acidity of the solution until a slightly alkaline medium is created. The creation of such an environment is necessary for the best dissolution of chalk (CaCO ₃ ) in it, with which the following occurs: when the acidity is shifted towards the alkaline medium, calcium carbonate passes into calcium hydrogen carbonate, which is much better soluble in water.

The composition of the proposed buffer solution will be as follows: Na ₂ B ₄ O ₇ * 10H ₂ O + CaCO ₃ . This buffer solution has the following properties: accessibility and cheapness, as well as increased fire extinguishing effect. When this solution acts on the combustion zone, several reactions will occur at once: CaHCO ₃ will dissociate in water into Ca (OH) ₂ and H ₂ CO ₃ , which will immediately decompose into H ₂ O and carbon dioxide (it is a combustion inhibitor), and Under the influence of temperature, Ca (OH) ₂ decomposes into CaO and water, spending energy on this and cooling, thereby, the combustion zone, which prevents the further spread of the fire.

In order to create a buffer solution with the required pH, it was necessary to calculate at what value the maximum amount of CaCO ₃ passes into CaHCO ₃ .

As the pH in the solution of a weak dibasic acid changes, the equilibrium dissociation of the acid shifts in one direction or another, and the concentrations of undissociated H ₂ An molecules and the HAn ^- and An ^-2 anions change.

If the pH of the solution and the concentration of hydrogen ions [H ⁺ ] are known, then it turns out to be convenient to calculate the fractions of the forms of dissociation of dibasic acid a ₀ , a ₁ , a ₂ :

where C _H2An , C _HAn-1 , C _An-2 are the concentrations of hydrogen ions in solution.

Substituting the values of K ₁ and K _total in the equation of material balance, we obtain the concentration of undissociated molecules of H ₂ An:

and from here we find

Similarly, we find

These equations make it possible to calculate the fraction of one form or another of dissociation of dibasic acid at any concentration of hydrogen ions in solution. Knowing these fractions and C _H2An , it is easy to calculate the concentrations of [H ₂ An], [HAn ^- ] and [An ^-2 ].

Note that in strongly acidic solutions, when [H +]> K ₁ , a ₀ = 1. This can be seen from the equation for calculating a ₀ . With increasing pH, the proportion decreases and the proportion of a ₁ increases.

This condition follows from the equations for calculating a ₀ and a ₁ . With a further increase in pH, a ₀ continues to decrease, a ₁ increases and reaches a maximum at

With a further increase in pH, the fraction of a ₁ begins to decrease, and the fraction of a ₂ begins to increase. At pHpK ₂ equality occurs: a ₁ = a ₂ . This follows from the equations for calculating a ₁ and a ₂ . With a further increase in pH, the fraction of a ₁ continues to decrease, and the fraction of a ₂ continues to increase. Thus, knowing the pH in a solution containing a dibasic acid, it is possible to determine which form of the acid predominates in the solution: undissociated acid, dissociated by stage I or completely dissociated. You can also find out at what pH values the solution contains two forms of acid in comparable concentrations. So, at a pH of 1 to 5, undissociated H ₂ CO ₃ is predominantly present in the solution, at a pH of 7 to 9 - HCO ₃ , at a pH of 11 to 13 - CO ₃ ^-2 .

и $$C{O}_3^{-2}$$

при заданных значениях pH, можно констатировать, что мольная доля $$HC{O}_3^{-}$$

максимальна в интервале pH 7-10, а $$C{O}_3^{-2}$$

- при pH более 12.Comparing the results of a simple calculation of the molar fractions of anions $$HC{O}_3^{-}$$

and $$C{O}_3^{-2}$$

at given pH values, it can be stated that the mole fraction $$HC{O}_3^{-}$$

maximum in the range of pH 7-10, and $$C{O}_3^{-2}$$

- at pH greater than 12.

According to the calculations, it was determined that in order to obtain the most saturated CaHCO ₃ solution, it is necessary to create a solution acidity level from 6.5 to 10.3. Under these conditions, the maximum fire extinguishing effect will be achieved, as the energy released by the fire will be spent on the decomposition of more Ca (OH) ₂ .

Thus, the fire extinguishing effect is achieved by cooling (emitted as a result of heating of the buffer solution with water by the fire), dilution (emitted by heating the fire of the buffer with carbon dioxide), and by chemical inhibition of the combustion reaction, since a large amount of energy is spent on the destruction of intermolecular bonds CaHCO ₃ .

The proposed method of extinguishing allows you to extinguish large areas of fire with the help of specialized aircraft (for example: air protection: AN-2, MI-8; Ministry of Emergency Situations - amphibians and Il-76TD) and the composition used can increase fire extinguishing efficiency and extinguishing times several times at a lower specific consumption . This is achieved due to the fact that calcium bicarbonate formed in water decomposes into calcium oxide nanoparticles, while the cooling effect is exerted on the combustion zone, carbon dioxide evolution occurs as a result of physicochemical processes, thereby causing a phlegmatizing and insulating effect. Boron compounds have a powerful inhibitory effect. In addition, when the proposed fire extinguishing solution gets on the surface, a strong nanoscale protective layer is formed, consisting of boron and calcium oxide compounds, which can only be destroyed mechanically.

When using the proposed solution for extinguishing forest tracts and peat bogs by any method of supplying to the foci of combustion, four basic quenching mechanisms immediately begin to work, namely cooling, isolation, dilution, and inhibition of the ongoing reactions. These extinguishing mechanisms are implemented thanks to the components of the proposed composition. In addition, due to the fact that the composition has a high pH and additives that inhibit heterogeneous combustion processes, it is able to penetrate into the thickness of forest litter and / or peat mass in a very short time and to eliminate and, subsequently, not to allow the occurrence of heterogeneous foci of burning (foci of decay).

Claims (8)

1. A fire extinguishing solution prepared on the basis of water, characterized in that it contains salts of boric and / or phosphoric acid, as well as calcium and / or magnesium carbonates in pure form or in the form of rocks or industrial wastes containing them, the pH of the solution being ranging from 6.5 to 10.3. 2. Fire extinguishing solution according to claim 1, characterized in that the pH of the solution is in the range from 9 to 9.5. 3. The fire extinguishing solution according to claim 2, characterized in that it contains water 1 m ³ , sodium tetraborate 10.1 kg, calcium carbonate 1.6 kg. 4. A method of extinguishing a fire, comprising supplying a fire extinguishing solution to a fire, characterized in that the fire extinguishing solution contains salts of boric and / or phosphoric acid, as well as calcium and / or magnesium carbonates in pure form or in the form of rocks or industrial waste, their containing, and the pH of the solution is in the range from 6.5 to 10.3. 5. The method of extinguishing a fire according to claim 4, characterized in that the pH of the solution is in the range from 9 to 9.5. 6. The fire extinguishing method according to claim 5, characterized in that it contains water 1 m ³ , sodium tetraborate 10.1 kg, calcium carbonate 1.6 kg. 7. The fire extinguishing method according to claim 6, characterized in that the extinguishing solution is supplied to the fire by spraying with the help of specialized aircraft. 8. The method of extinguishing a fire according to claim 6, characterized in that the extinguishing solution is supplied to the fire by discharge or discharge using specialized aircraft.