WO2015051917A1

WO2015051917A1 - Liquid fire extinguishing agent and method for produing same

Info

Publication number: WO2015051917A1
Application number: PCT/EP2014/002742
Authority: WO
Inventors: Jens V. HABERMANN; Dmitri N MITJUSCHOW; Anatoly T KOPANEV
Original assignee: Habermann Jens V; Mitjuschow Dmitri N; Kopanev Anatoly T
Priority date: 2013-10-09
Filing date: 2014-10-09
Publication date: 2015-04-16
Also published as: DE102013111142A1

Abstract

The invention relates to a method for increasing the efficiency of a fire extinguishing liquid comprising an aqueous solution of ammonium sulfamate, sulfaminic acid, urea, ammonia, alkali salts, and carbonates, bicarbonates and phosphates of potassium and sodium. To achieve this, the salts that enter the pores of the burning material create conditions for forcing oxygen out of the pores of the burning material.

Description

The invention relates to a liquid fire-extinguishing agent and a method for the production thereof.

The invention belongs to the flame retardant (impregnation) and fire extinguishing water solutions for the extinguishment of class A and B fires.

As is well known, water is the fire extinguishing agent used most as a fire extinguishing agent. The advantages of water as a fire extinguishing agent, in addition to its accessibility and low cost, are considerable heat capacity, high latent heat of vaporization, fluidity, chemical neutrality and non-toxicity. At very high temperatures, however, water vapor can decompose with a hydrogen splitting.

CONFIRMATION COPY The fire-extinguishing power of water is caused by the following effects: cooling effect, dilution of the combustible medium, accumulation of vapors during evaporation of water and mechanical action on the burning material, ie flame-rupture.

Among the major disadvantages of water in this context include its inadequate wettability and low viscosity. These properties make it difficult to extinguish fibrous, dusty and, above all, smoldering materials. The most susceptible to smoldering are materials with a large specific surface area. Their pores contain the air needed for burning. Such substances are well combustible even with very low levels of oxygen in the environment. The extinguishing agents are usually difficult to penetrate into the pores of smoldering substances.

For this reason, the fire extinguishing agent is supplemented with smoldering fire with various additives in order to increase the fire extinguishing effect. These include, in particular, surface-active substances and foaming agents as well as numerous wetting agents.

In "Römpp ^'s Chemie Lexikon", 7th ed. 1975, page 3392, left column, sulfamic acid is, among many other uses also the use in (powdered) fire extinguishing agents (for freeing carbon dioxide from carbonates) or Production of flame retardants pointed out.

That the addition of urea to fire extinguishing agents their extinguishing effect and their flame retardancy can be improved, is also known. In addition, there are flame retardants containing a combination of sulfamic acid salt and urea. DE 3517091 discloses a water-based liquid flame retardant which contains, in addition to ammonium sulfamate and urea, fatty acid salts, cumene sulfamate, alkyl polyglycol and surface-active substances. A disadvantage of this aqueous flame retardant is that its preparation is very complicated: First, an aqueous solution of sulfamate (solution A) must be prepared. To introduce the fatty acid derivatives into this solution, mixtures of the surfactants must be prepared (Solutions B, C, D) since the fatty acid ethers do not mix with the water. Immediately before use, the solutions A + B, A + C, A + D are then mixed.

US 2212152 also describes a fire-extinguishing aqueous solution containing urea and sulfamic acid. A disadvantage is the complex treatment process with control of the temperature parameters during the process. In addition, toxic gases and water-insoluble substances (melamine and cyanuric acid) are formed during reprocessing, which necessitates filtration during the treatment of the solutions.

The use of alkali salts as wetting agents in fire-extinguishing liquids is known: DE 1214986 describes a fire-extinguishing liquid with one of a phosphate (having a pH of 3 to 6) and an alkali salt (eg sodium sulfate) for application to (in particular pulp-containing) flammable items. Among the shortcomings of this fire extinguishing liquid is the extremely limited application: disclosed is only the use for the impregnation of cellulosic, combustible objects such as. Paper. In addition, the costly compound hydroxybutyramide is included. Another disadvantage is the acidity of the composition with a pH of 3 to 6.

From JP 2013104058 a fire-extinguishing agent in powder form is known, which in addition to sulfamic acid salt also contains an alkali metal salt. Since there are fundamentally other problems with extinguishing powders compared to extinguishing liquids, however, no transferability can be derived from this and no usable information for the Suitability of one or more specific salts or esters of this acid for use in an aqueous fire-retardant.

The closest prior art (RU 2 418 61 1 C1) to the invention is a fire extinguishing composition containing urea, ammonium sulfate and sodium bicarbonate surfactant (s), ammonium silicate, ammonium chloride, sodium sulfate, alunite and fatty acids. The composition is a powder which is dissolved in water. It contains a propellant and is used as a foam. This combined fire extinguishing composition is capable of stopping the burning of various materials thanks to the combined action of certain fire stopping mechanisms. It involves three out of four extinguishing mechanisms known in practice: cooling, thinning and asphyxiation of the firing range. However, the cited prior art has an inadequate efficiency in firefighting, because it does not cover the main fire-stopping process, namely inhibition.

The object underlying the invention was a fire extinguishing agent with an improved fire-extinguishing effect and a fire-retardant effect. In addition, the process for producing the fire-extinguishing agent should be less complicated than the processes known in the prior art.

This object is achieved by the fire extinguishing agent according to claim 1 and the method for its production according to claim 6. Advantageous design features are shown in the dependent claims.

The invention relates to water-based fire-retardant and fire-extinguishing agents to extinguish the burning of substances, especially with a porous structure. The main ingredients of the multi-effect fire-extinguishing liquid are sulphamic acid salt, Urea, and alkali salt, such as or carbonate and bicarbonate, phosphate of potassium and sodium.

The combination of alkali salts with sulfamic acid salt and urea has the surprising technical effect that the salts penetrating into the pores of the burning material create conditions to displace oxygen from the pores of the burning material, thus improving the efficiency of the fire-retardant (condensed) effluent Phase and in the flame phase) as well as to achieve an improved fire extinguishing effect. The fire-extinguishing solution according to the invention is thus particularly suitable for combustible substances with a porous structure.

The sulfamic acid salt should preferably be ammonium sulfamate formed from amidosulfonic acid and ammonia. Ammonium sulfamate belongs to the category of fire-retardant preparations and contributes to the effective penetration of ammonium salts into the pores of burning, smoldering substances. However, it has no gas phase inhibitory power.

Using the mentioned ingredients, the invention solves the problem of fire retardation in the condensed phase and inhibition in the flame phase. This requires a high efficiency of both the fire-protecting and the fire-extinguishing properties of this liquid.

In order for the liquid to penetrate into the pores of the burning substance and displace the air from it, the ammonium salts must get into the pores. Ammonium salts are formed during the interaction of ammonia or its water solutions with acids, for example: NH ₃ + HNO ₃ = NH ₄ NO ₃

NH ₃ * H ₂ O + HNO ₃ = NH ₄ NO ₃ + H ₂ 0

or in ionic form:

NH ₃ + H + = NH ₄ +

NH ₃ * H ₂ O + H + = NH ₄ + + H ₂ 0

They have common properties for all salts, namely a combination with alkaline solutions, acid solutions and other salt solutions:

NH ₄ Cl + NaOH = NaCl + H ₂ O + NH ₃ †

2NH ₄ Cl (k) + H ₂ S0 ₄ = (NH ₄ ) 2 SO ₄ + 2 HCI †

(NH ₄ ) 2SO ₄ + BaCl ₂ = BaSO ₄ + 2NH ₄ Cl. All ammonium salts are decomposed or sublimed when heated, e.g. For example:

(NH ₄ ) 2C0 ₃ = 2NH ₃ † + H ₂ O + C0 ₂ †

NH ₄ N0 ₂ = N ₂ † + 2H ₂ O NH ₄ Cl 'NH 3 + HCI †

The ammonium salts are readily soluble in water. In the water solutions they are exposed to hydrolysis. Therefore, the ammonium salt solutions of strong acids have a pronounced acid reaction:

NH ₄ + + H ₂ O NH ₃ + H ₃ O +

To increase the fire-fighting power of the liquid, it is supplemented with alkaline substances. The inhibiting effect of the alkaline additives is due to the fact that the most important chain carrier in the development of the chain reaction during combustion is the OH radical. The alkaline medium (for example, water with the additives soluble in it at pH values of the medium of 8 to 9) is most similar to this OH radical and thus is able to inhibit the reaction in the flame by removing the OH radicals be destroyed. In an acidic medium with pH = 3 begins an intense sulfamate decomposition. In this medium, the urea hydrolysis is suspended. This ammonia is developed. This increases the pH abruptly and thus prevents the degradation of sulfamate.

Θ

OH O

I i

o = s = o o = s = o

I i

NH ₂ ® NH ₃

JOURNAL OF FIRE SCIENCES, VOL. 15- JUL

OH

O II N N

3 H ₂ N-C-NH ₂ 3 NH ₃

HO N OH

The urea trimerization temperature is above 250 ^° C.

The melting temperature of cyanuric acid is 360 ^° C. This causes a simultaneous charring. Sulfamic acid M = 97.09 g / mol

Urea M = 60.07 g / mol

P 28% ammonia solution = 0.8980 g / ml. The solution contains about 0.25 g of ammonia in 1 ml.

example 1

1 l of water is supplemented with 97 g of sulfamic acid. Thereafter, 60 g of urea is added with stirring. Then the solution is carefully supplemented with 10 ml of 28% ammonia (1). The result of this process should be the preparation of a pH = 8-9 solution close to an alkaline solution.

(1) First, a sulfamic acid urea salt is formed. Thereafter, a mixture of ammonium sulfamate, urea sulfamate and urea is formed. At this pH should be checked.

With a small surplus compared to the required amount, because it is weatherable when storing.

Example 2

97 g of sulfamic acid is added to 1 liter of water. Thereafter, 70 ml of 28% ammonia is added to the solution with stirring. Then the solution is supplemented with 6 g of urea. The result is the preparation of a time stable solution with pH ~ 9. [See (1) Example 1]

Examples 3 - 7

6 - 59 g of urea and, accordingly, 1 1 - 65 ml of 28% ammonia. Examples 8-12

As in Example 2, however, the mass of urea is 0, 1-5.9 g. Examples 13-17

Concerning dilution and concentration of solutions

Elemental analysis of the fire extinguishing agent. During the atomization of the extinguishing aerosol in the flame, the solution is dehydrated in the hot fire area or on the heated surfaces, so that salt crystals are formed. Thereafter, an elemental analysis of the residue was made. The fire-extinguishing solution was filled in a dish. After evaporation of water, the residue was analyzed by scanning electron microscope.

The results of the residue analysis are shown in FIG. 8. The table below gives details of this analysis.

Elementary analysis of the residue

(NH ₄ ) ₂ SO ₄

Element wt.,% Atom. ,% Ammonium sulfate

During spectral processing, the peaks of 0, 143, 0.940, 8.048 keV were omitted. The last two lines refer to the atomic lines of copper, the thin film of which has been deposited like a film on the sample to allow scanning in the EM. The first peak (refers to) small amounts of atoms of an alkali metal or boron. In terms of the peak ratio, ammonium sulfate is the most likely raw material. Thermoanalytical measurements

DTA-MS (differential thermal analysis mass spectrometry), temperature range 45-600 ° C, heating rate 10 ^° C / min.

A sample was prepared which was prepared by evaporation on 20.10.2012. (Fig. 1)

Ammonium sulfamate NH ₄ (S0 ₃ NH ₂ ) Melting point 125 ° C; Removal start at 160 ° C.

Sodium carbonate Na ₂ C0 ₃ - Melting temperature of pure compound 820 ° C.

(FIGS. 2a, 2b, 3a, 3b)

M SO ₂ = 64 MN ₂ = 28, M CO = 28 (44-16) (FIG. ₂ b) The proportion of sulfamic acid is about 95% (FIG. 3 b)

MH ₂ O = 18, M NH ₃ = 17 (FIGS. 16 and 14: the 1st and 3rd ionization potentials) (FIG. 5b) The diffraction image was taken in the channel Cl.

(Diffraction cinema, Sharafutdinov M.R.)

A sample was prepared which was prepared by evaporation on 20.10.2012. (Figures 6a and 6b)

The identified ingredients are ammonium amidosulfate and possibly a mixture of potassium and sodium carbonates or hydrocarbonates, and possibly a sulfate admixture.

When adding water and salt aerosol, the burning rate of the methane-air mixture is significantly reduced. This can be seen in FIGS. 7 and 8. These figures contain test results for flames that are close to stoichiometry. From the figures it can be seen that the flame propagation Speed is further reduced after salt addition to the water. Since the salt is a solid aerosol, the rate is given in mg / m ³ . The water is completely evaporated and is given in volume percent. Fig. 7 shows the dependence of the burning rate of water vapor.

Methane-air flame, phi = 1, 2. TO = 93 ° C

Fig. 8 shows effectiveness of inhibition of the methane-air flame by flame-extinguishing agents for phi = 1, 2, T0 = 93 ° C

The work on the optimization of the fire extinguishing systems and the forecast of the fire safety presuppose the information about the change of the burning speed depending on the initial conditions. Typical representation in engineering calculations is as follows:

is there

TO = 25 ° C,

PO = 1 atm,

C = 0.0 1 [H ₂ O] - experience factor and water mass concentration,

D = 0.017 [KFL] (concentration of the fire extinguishing agent) - experience factor and mass concentration of the additives g / m ³ .

In contrast to the poor flame, the fat flame spreads with predominant heat mechanism. Therefore, the influence of salts is less significant than the influence of water vapor. After all, the burning rate is just as intense with an increase in the concentration of additives.

The influence of aerosol of a dissolved chemically active flame retardant (liquid under investigation) on the flame propagation researched the speed of the methane-air mixture. It was found that its introduction into the stoichiometric methane-air mixture reduced the flame velocity over a wide range of the stechiometric coefficients.

For example, with the addition of 2.2% of water vapor, the flame propagation velocity of the stoichiometric combustible methane-air mixture decreases by 8%. With an addition of 2.2% of water vapor and 0.2 g / m ^{3 of} salt, a further higher reduction in flame propagation speed by 25% is observed. The results indicate that small additions of the fluid exert a significant inhibitory effect on the flame propagation velocity of the methiochlorochemical stoichiometric mixture, both computationally and experimentally. From the results obtained, it can be concluded that the use of such an inhibitor instead of the conventionally used water enables more effective extinguishment and prevention of methane ignition.

On the basis of the research carried out, the relationship between the burning rate and the concentration of the investigated liquid solution in the flame compared to water was determined by the optical PIV method.

The 8% concentration of the liquid solution at the phlegmatizing tip is 240 g / m ³ . The fire-extinguishing mass concentration of the solution with a 30% active ingredient content is about 40 g / m ³ . That's six times more effective than water.

Comparative research was conducted to determine the change in liquid efficiency during fire extinguishment. It has been found that it is precisely the increase in the transition of the volatile flame retardants into the gas phase that shifts the second exothermic effect of the fire protected wood in the direction of higher temperatures. This happens because the oxidation processes in the flame are suppressed. As a result, the heat flow to the combustible material decomposing in the condensed phase also decreases.

It has been the predominant stage of wood extinction, namely the inhibition of radical processes in the flame area by volatile nitrogen compounds. The decrease in the exothermic effect of the oxidation reaction in the gaseous phase, the temperature drop and the loss of the flame propagation capability of the gas mixture of fuel and oxidant are due to the attenuation of the flow of the gaseous fuel from condensed phase, dilution of the fuel by non-combustible products of polymer and additive degradation so- as a result of the inhibition of chemical reactions in the flame.

The deposition of combustion products from the flame region is accompanied by considerable heat losses. A number of compositions in the form of multi-component water solutions comprising nitrogen-containing compounds are known in the art: ammonium phosphate and bisphosphate salts, ammonium sulfate, urea, and some other components (UK Patent 2301,122, A62D 1/00, D06M 1 1 / 79, publication date 27.1 1.1996); Tris-aziridinil-phosphine oxide, cyanamide, ammonium salts of phosphoric, amidosulfonic, sulfuric or hydrochloric acid (Patent Application DE 2028999, D06M 13/00, 16.12.1971). The multicomponent composition of the preparations causes their increase in cost and a difficulty in the production process. The ammonium sulfamate is used as a combustion retarder in paper treatment compositions. It is usually added with the addition of used to remove such deficiencies of products treated with ammonium sulphamate solution, such as loss of strength, insufficient penetration of the solution into the products, discolouration of the products, simple leaching of the preparations from capillaries and a lack of gas shielding of the products.

The following ammonium sulfamate-based preparations are known from the prior art:

Water solution of ammonium sulfamate and dicyandiamide (US Pat. No. 2,771,379, D06M 13/00, publication date 20.1 1. 1956);

Water solution of ammonium sulfamate, dicyandiamide, boric acid, water-repellent agent Werner complex (US patent 2723212 D06M 1/66, D06M 1/24, publication date 08.1 1 .1955);

Water solution of borax, diammonium phosphate and ammonium sulfamate mixture (JP Patent 7204752, D06m, published on Feb. 9, 1972,

CA, 1972, vol.77, 127991);

Water solution of 1 M ammonium sulfamate and 0.5-1 M dicycranediamide (Japanese Patent Application 89139900, D21 H 5/00, published on May 10, 1989, CA 1989, vol. 1131, 235448);

Water solution of ammonium sulfamate and dicyandiamide (Japanese Patent Application 83109577, C09K 3/28, published 29.06.1983, CA. 1984, vol. 100, 8450);

Water solution of ammonium sulfamate and urea (Japanese Patent Application Laid-Open No. 8082688, B41 M 3/12, publication date 21/06/1980, CA. 1980, vol.93, 169610);

Water solution of ammonium sulfamate, borax and phosphoric acid (CA patent 983225, 18-1 13,017, published on 10.02.1976, CA. 1976, vol.84, 166125);

- Water solution of polyphosphoric acid (84% P2O5), ammonium sulfamate and urea (Japanese Patent Application 7413499, 48D8, 39D212, publication date 05.02.1974, CA. 1974, vol.81, 122688). These agents belong to the category of fire retardant preparations. The broad use of ammonium sulfamate in these agents contributes to the effective penetration of the ammonium salts into the pores of burning, sloshing substances. However, they have no gas phase inhibitory power.

Claims

speak

1. Liquid fire extinguishing agent based on water,

full

(a) sulfamic acid salt,

(b) urea,

(c) at least one alkali salt,

wherein the alkali metal salt is selected from potassium and sodium carbonates, bicarbonates and phosphates.

Fire extinguishing agent according to claim 1 or 2,

wherein the sulfamic acid salt is ammonium sulfamate.

Fire extinguishing agent according to one of claims 1 to 3,

wherein the pH is in the range of 7 to 9.

Process for the preparation of a liquid fire-retardant according to one of the preceding claims,

comprising the following steps:

(a) First, sulfamic acid, then urea is added to water;

(b) adding ammonia to the solution of (a)

(c) adding at least one alkali metal salt to the solution of (b);

(d) Adjusting the pH of the solution from (c) to pH = 7-9. Method according to claim 5,

comprising the following steps:

(a) First, 97 grams of sulfamic acid, then 60 grams of urea are added to 1 liter of water;

(b) adding 10 ml of 20% ammonia to the solution of (a)

(c) adding at least one alkali metal salt to the solution of (b);

(d) Adjusting the pH of the solution from (c) to pH = 7-9.

A fire fighting method comprising contacting a fire-extinguishing and fire-retardant liquid comprising sulfamic acid salt, urea and alkali salt with a burning material, the salts penetrating into the pores of the burning substance providing conditions to displace oxygen from the pores of the burning material.