CN102029040A - Complex additive used for extinguishment with water mist - Google Patents

Abstract

The invention relates to a composite additive for fine water mist fire extinguishing, the formulation of which is composed of three different substances: alkali metal salts, surfactants and diluents according to the different action mechanisms of the additives; the alkali metal salts It is: a mixture of at least two or more of potassium carbonate, sodium carbonate, sodium phosphate, sodium lactate, and sodium iodide, and the alkali metal salt accounts for 1% to 3% of the total mass fraction of the additive solution; the surface active The agent is one of sodium dodecylbenzenesulfonate, coconut oil diethanolamide or a mixture of the two, and the surfactant accounts for 0.5% to 1% of the total mass fraction of the additive solution; the diluent is One of urea and ammonium bicarbonate or a mixture of the two, the diluent accounts for 0.5% to 1% of the total mass fraction of the additive solution. The preparation process of the invention is simple, can be quickly dissolved without adding organic solvents, has high fire extinguishing efficiency, does not corrode fire extinguishing field equipment, and can be widely used in fine water mist fire extinguishing systems and fire extinguishing places in various occasions.

Description

A composite additive for fine water mist fire extinguishing

technical field

The invention relates to a composite additive for fine water mist fire extinguishing, which relates to a fine water mist fire extinguishing additive for fire fighting, which can be widely used in various fixed and portable fine water mist fire extinguishing systems, and can be added to ships or In the high-pressure single-phase flow or two-phase flow fine water mist fire extinguishing system in the submarine, it can improve the fire extinguishing efficiency.

Background technique

Water mist mainly relies on physical action to extinguish fire. In order to further improve the fire extinguishing efficiency of water mist, water mist containing additives has become a new hot spot of research at home and abroad in recent years. Introduce an additional physical and chemical fire extinguishing mechanism in the fine water mist, that is, selectively add one (or several) organic (or inorganic) compounds to the water to change the physical and chemical properties of the fine water mist and improve the performance of the fine water mist. Fire extinguishing efficiency, in order to achieve better results, this is the so-called additive-containing fine water mist. According to different fire extinguishing mechanisms, additives can be divided into two categories. One is physical action additives, which mainly improve the atomization characteristics and fire extinguishing efficiency of water by changing the physical properties of water such as density, viscosity, and surface tension. The purpose of water mist fire extinguishing ability. The second category is chemical action additives, mainly by capturing free radicals such as hydrogen, oxygen, and hydroxyl in the combustion process, interrupting the combustion reaction chain and generating suffocating gas in a chemical reaction in the fire scene, and finally achieves the purpose of extinguishing the fire. The addition of fire extinguishing additives can not only give full play to the physical fire extinguishing advantages of fine water mist, but also realize the synergistic fire extinguishing with additives, so the fire extinguishing time can be greatly shortened. Generally speaking, chemical fire extinguishing additives mainly composed of metal compounds and transition metal compounds have the most obvious fire extinguishing effect, and their fire extinguishing ability is about one to two orders of magnitude higher than that of Halon 1301 (CF ₃ Br). The data show that the fire extinguishing mechanism of water mist fire extinguishing additives is a complex coupling of chemical fire extinguishing and physical fire extinguishing, and the fire extinguishing effect of water mist containing additives has been significantly improved. It is a new content of fire extinguishing technology research, but the additive-containing water mist fire extinguishing system is still under development and exploration.

At present, the fine water mist additives that have been studied at home and abroad mainly include: alkali metal compounds (such as sodium lactate, sodium chloride, potassium hydroxide, alkali metal carbonate, etc.), iron-containing organic compounds and salts (such as iron pentacarbonyl [Fe (CO) ₅ ], ferrocene [Fe(C ₅ H ₅ ) ₂ ], ferric chloride, etc.), other transition metal elements (such as chromium, cobalt, lead, manganese, tin) compounds, ammonium salts (such as ammonium phosphate , ammonium carbonate, etc.), surfactants (such as fluorocarbon surfactants, sodium dodecylbenzenesulfonate, etc.), binders (such as polyvinyl alcohol, polyacrylamide), etc. Among them, metal elements mainly interrupt the combustion reaction by capturing free radicals such as hydrogen, oxygen, and hydroxyl in the combustion chain reaction process. Such substances have a strong chemical fire extinguishing effect; ammonium salts and bicarbonates will Thermal decomposition releases a gas that is neither flammable nor combustion-supporting, dilutes the concentration of oxygen around the fuel, and strengthens the suffocation effect of fine water mist; the surfactant can greatly reduce the surface tension of water, improve the atomization effect, and can Form a layer of film, on the one hand, reduce the heat feedback of the flame to the fuel surface, on the other hand, directly prevent the volatilization of combustible gas, isolate the fuel from oxygen, and play the role of isolating oxygen and inhibiting combustion; Viscosity to increase the momentum of fine water mist droplets, thereby improving their ability to penetrate high-temperature flue gas.

Alkali metal salts are currently the most researched additives. The fire extinguishing performance of a single additive is sodium iodide, sodium phosphate, sodium lactate, sodium carbonate, and potassium carbonate in order from weak to strong. It can be seen that the activity of potassium element is stronger than that of sodium element. Kinetic studies show that the combination of K and OH is 30% faster than that of Na and OH, and the combination of K and _O2 is 2-3 times faster than that of Na and _O2 . Studies have pointed out that the fire extinguishing ability of alkali metals increases with the increase of atomic weight. When urea and ammonium bicarbonate are heated and decomposed at high temperature, they will release non-combustible gases such as ammonia and carbon dioxide, so as to achieve the purpose of diluting oxygen and gas. In addition, changing the survival time of water mist in the fire scene, dry particles colliding with free radicals to capture free radicals are all potential fire extinguishing mechanisms. Ferrocene is a high-efficiency fire extinguishing additive, and it has good fire extinguishing performance at hundreds of ppm. The extinguishing time of 0.01% ferrocene is equivalent to that of 1.5% alkali metal salt. Although ferrocene has a good fire extinguishing effect, because it is an insoluble substance, a large amount of organic solvent needs to be added to dissolve it, and then it needs to be filtered. Therefore, when choosing it as a fine water mist additive, various aspects should be weighed.

Composite additives refer to fine water mist additives prepared by preparing different types of fine water mist additives according to different concentrations. However, its fire extinguishing efficiency is not a simple superposition of the fire extinguishing efficiencies of various additives. There are interactions between different additives of the same type and between different types of additives. This interaction can be either reinforcement or competition, and there is no research on the fire extinguishing mechanism of compound additives yet.

Contents of the invention

The purpose of the present invention is to propose a composite additive for fine water mist fire extinguishing, to overcome the defects of low fire extinguishing efficiency and fire site pollution in the prior art.

A composite additive for fine water mist fire extinguishing according to the present invention is characterized in that its formula is composed of three different substances: alkali metal salts, surfactants, and diluents, according to the different action mechanisms of the additives;

The alkali metal salt is: potassium carbonate, sodium carbonate, sodium phosphate, sodium lactate, sodium iodide at least two or a mixture of various alkali metal salts, and the alkali metal salt accounts for 1% of the total mass fraction of the additive solution ~3%;

The surfactant is one of sodium dodecylbenzenesulfonate and coconut oil diethanolamide or a mixture of the two, and the surfactant accounts for 0.5% to 1% of the total mass fraction of the additive solution;

The diluent is one of urea and ammonium bicarbonate or a mixture of the two, and the diluent accounts for 0.5% to 1% of the total mass fraction of the additive solution.

Among them, the ion types of the alkali metal salt additives should be diversified, and the diluent should be selected from substances with a low decomposition temperature and long-term storage.

The mass concentration of this composite fire extinguishing additive is low, and the additives with different fire extinguishing mechanisms can play the greatest role, and the fire extinguishing efficiency can reach up to 4 times that of pure water mist. This composite additive is simple to prepare, easy to dissolve, and has no corrosion to equipment, and can be applied to fixed water mist fire extinguishing systems and portable fire extinguishing systems.

Single additive fire extinguishing effect test

The present invention first uses different kinds of alkali metal salts and diluents to test the fire extinguishing efficiency of a single additive. The following table lists the time required for a single additive to extinguish a 0.44MW heptane fire under a pressure of 4MPa when the concentration of a single additive is 1.5%.

Additives Concentration extinguishing time Sodium carbonate 1.5% 21.0(s) Sodium Lactate 1.5% 22.7(s) Sodium Phosphate 1.5% 27.3(s) Sodium iodide 1.5% 27.3(s)

potassium carbonate 1.5% 19.3(s) Urea 1.5% 43.7(s) ammonium bicarbonate 1.5% 48.3(s) pure water -- 57.7(s)

Through the fire extinguishing experiment of n-heptane, it shows that among alkali metal salts, potassium carbonate and sodium carbonate have the best fire extinguishing effect when used as additives. When the diluent acts alone, the fire extinguishing effect is not greatly improved.

Alkali metal salt complex test

Additives Concentration extinguishing time Sodium Carbonate + Potassium Carbonate 0.75%+0.75% 16.3(s) Potassium Carbonate + Sodium Phosphate 0.75%+0.75% 15.7(s)

In the single additive fire extinguishing experiment, potassium carbonate has the strongest fire extinguishing performance, and sodium phosphate has the weakest fire extinguishing performance. However, after combination, the total mass fraction of alkali metals is still 1.5%, but the fire extinguishing time of composite action is shorter than that of any component alone. The fire extinguishing performance of sodium carbonate is stronger than that of sodium phosphate, but the fire extinguishing performance of the combination of potassium carbonate and sodium carbonate is not as good as the combination of potassium carbonate and sodium phosphate. Therefore, both anions and cations have a saturated concentration in the fire scene, and the lower the concentration, the greater the efficiency of their function. Therefore, during the preparation of additives, the ion types of alkali metal salts should be varied.

Fire extinguishing effect test of alkali metal salt + diluent

Different concentrations of alkali metal salts and diluents were used to test the compound effect and the influence of different concentrations on the fire extinguishing effect. The following table lists the effects of different diluents and alkali metal sodium carbonate salts on fire extinguishing effectiveness.

Additives Concentration extinguishing time Sodium carbonate + urea 1.5%+1.5% 21.7(s) Sodium Carbonate + Ammonium Bicarbonate 1.5%+1.5% 17.3(s)

From the test results of different diluents and sodium carbonate compound effects, it can be seen that when the diluent and alkali metal salts act together, when the diluent uses urea, the fire extinguishing time is equivalent to that of alkali metal salts alone, and the fire extinguishing effect of urea is surpassed by alkali metal salts. However, when ammonium bicarbonate is used, the fire extinguishing performance is significantly improved, and the decomposition temperature of ammonium bicarbonate is lower, and it reacts with the flame before the alkali metal salt. Therefore, when choosing a diluent, a substance with a lower decomposition temperature should be selected.

The following table has listed the impact of different mass concentrations of alkali metal salts on the fire extinguishing effect when the mass concentration of ammonium bicarbonate is 1.5%.

Additives Concentration extinguishing time

Potassium Carbonate + Sodium Carbonate + Ammonium Bicarbonate 1.5%+1.5%+1.5% 15(s) Potassium Carbonate + Sodium Carbonate + Ammonium Bicarbonate 0.75%+0.75%+1.5% 15(s) Potassium Carbonate + Sodium Carbonate + Ammonium Bicarbonate 0.5%+0.5%+1.5% 17(s)

Under the condition of fixed concentration of ammonium bicarbonate, the fire extinguishing effect of alkali metal salt is equivalent when the total concentration is 1.5% and 3%, and the fire extinguishing time is slightly increased when the total concentration is 1%. Alkali metal salts tend to be saturated when the total concentration is 1.5%. Under the condition of the same mass concentration, the fire extinguishing time of alkali metal salt complex action is shorter than that of any component acting alone. At the same time, both anions and cations have a saturated concentration in the fire scene, and the lower the concentration, the greater the efficiency of their function. Therefore, during the preparation of additives, the ion types of alkali metal salts should be varied.

Compared with the existing fine water mist fire extinguishing additives, the present invention integrates and improves several existing additives, learns from each other's strengths, and invents a formula that has most of the advantages of the existing additives and basically overcomes their defects. The additive components of the present invention mainly include the following categories: one is substances that can effectively increase the chemical fire extinguishing effect of fine water mist, such substances include thermally decomposed heat-sensitive substances and chemical substances that can interrupt the combustion chain reaction, such as alkali metal salts etc.; the second is the surfactant, which mainly improves the oxygen barrier effect of the fine water mist and reduces the thermal radiation of the flame, and at the same time reduces the surface tension of the fine water mist to improve the atomization effect; Medium heat decomposition can release gas that is neither combustible nor combustible, which can effectively reduce the oxygen concentration around the fuel and play a suffocating role. Because the first type of additive contains metal ions, it has the advantages that inorganic salt additives can effectively improve the fire extinguishing efficiency of fine water mist; the surfactant in the second type of additive can not only make the fine water mist form a layer of water on the burning surface The film isolates oxygen and radiation, and can effectively improve the surface tension of the water mist fire extinguishing medium, thereby improving the flow characteristics of the water mist, increasing the wetting ability of water to burning materials, and prolonging the action time of water; the third type of diluent can The release of suffocating gas can effectively reduce the fire reaction rate and reduce the temperature of the fire site below the critical oxygen concentration, which is of great significance for fine water mist fire extinguishing.

Advantage of the present invention and effect are as follows:

The fine water mist fire extinguishing additive of the present invention mainly utilizes surfactants and diluents to achieve the purpose of oxygen and temperature insulation, and there is basically no foam in the fire extinguishing process, so there is no pollution to the fire scene.

The fine water mist fire extinguishing additive of the present invention contains surfactants, diluents and various metal salts, not only has the efficient chemical fire extinguishing mechanism of metal ions, but also the surfactants and diluents can cool the gas phase, block flame heat radiation, The four fire extinguishing mechanisms of isolating oxygen and reducing the mixed concentration of combustible gas and air have a strong strengthening effect.

The basic principle for preparing the fine water mist fire extinguishing additive of the present invention is to achieve the best fire extinguishing effect at the minimum concentration. The vapor pressure of the alkali metal salt in the fire scene is very low, and when the concentration of the aqueous solution reaches a certain level, it will be basically saturated, and its mass fraction in the fine water mist generally does not exceed 5%. The present invention uses a variety of alkali metal salts, the total mass fraction of which is 1% to 3%. At this concentration, the problem of saturation concentration of anions and cations in the fire field is avoided, and at the same time, the interaction between additives under the same mechanism of action is avoided. Competitive effect, so that metal ions can exert the greatest fire extinguishing effect.

The surfactant in the water mist fire extinguishing additive of the present invention adopts sodium dodecylbenzenesulfonate or coconut oil diethanolamide, but its concentration should not be too large, generally not more than 1%, so that the viscosity of the fine water mist fire extinguishing additive remains suitable State, not only can fully atomize the fine water mist, give full play to the advantages of fine water mist fire extinguishing, but also can play the advantages of surfactant additives.

Detailed ways

Diluent selects the material with low decomposition temperature, present embodiment selects ammonium bicarbonate for use, and its concentration is 0.75%; Surfactant selects sodium dodecylbenzene sulfonate or coconut oil diethanolamide for use, considering the viscosity of surfactant itself , its concentration can not exceed 1%, and its concentration is selected as 0.5% in the present embodiment; Due to the existence of saturated concentration and mutual competition problems, the alkali metal salt should strive to be diverse in its kind, and its total concentration range is 1% to 3%. In this embodiment, two kinds of alkali metal salts are selected, the concentrations of which are both 0.75%, and the total concentration of alkali metal salts is 1.5%.

Example 1:

The water mist additives and their concentrations are shown in the table below.

Add the additive into pure water under slow stirring, and stir until completely dissolved. After filtering, inject the solution into the high-pressure water bottle, the inlet end of the high-pressure water bottle is connected with the high-pressure nitrogen cylinder group, and the outlet end is connected with the fine water mist nozzle. A 0.44MW oil pan is selected, the ceiling height is set to 3m, and a 1.8L/min (4Mpa) small flow nozzle is used to spray fine water mist containing additives to extinguish the fire.

The fire extinguishing time of embodiment 1 is shown in the column of fire extinguishing time in the table. The additive prepared by this formula is used for fire extinguishing, and the fire extinguishing time is 14 seconds, and the fire extinguishing efficiency is 4 times that of pure water.

Example 2:

The water mist additives and their concentrations are shown in the table below.

Its preparation method is with embodiment 1. Embodiment is the same as embodiment 1.

The fire extinguishing time of the additive in this embodiment is shown in the column of the fire extinguishing time in the table.

Example 3:

The water mist additives and their concentrations are shown in the table below.

Its preparation method is with embodiment 1. Embodiment is the same as embodiment 1.

The fire extinguishing time of the additive in this embodiment is shown in the column of the fire extinguishing time in the table.

Example 4:

The water mist additives and their concentrations are shown in the table below.

Its preparation method is with embodiment 1. Embodiment is the same as embodiment 1.

The fire extinguishing time of the additive in this embodiment is shown in the column of the fire extinguishing time in the table.

Beneficial effects of the present invention:

It can be seen from the results of the examples that when the fine water mist additive prepared by the formula of the present invention is used, its fire extinguishing efficiency is 3 to 4 times that of pure water mist. When sodium dodecylbenzenesulfonate is used as the surfactant, the fire extinguishing effect is stronger than that of coconut oil diethanolamide. When the composite additives are 0.5% sodium dodecylbenzene sulfonate, 0.75% potassium carbonate, 0.75% sodium carbonate and 0.75% ammonium bicarbonate, the fine water mist has the best fire extinguishing effect, and its fire extinguishing efficiency is the same as that of pure water mist. 4 times the efficiency.

The fine water mist fire extinguishing additive can be applied to both high-pressure single-phase flow fire extinguishing systems and two-phase flow fire extinguishing systems, and can be added to portable fire extinguishers at the same time. Turn on the fine water mist device to extinguish the fire. After the additive is sprayed out, a small amount of foam will be produced, but it will basically have no pollution to the environment and equipment. When used in ships and submarines, it has stable properties and rapid fire extinguishing, and can be used as a substitute for halon fire extinguishing agent.

Claims (1)

1. A compound additive for fine water mist fire extinguishing is characterized in that: its formula is to be made up of three different substances of alkali metal salts, surfactants and diluents according to the action mechanism of the additives; The alkali metal salt is: potassium carbonate, sodium carbonate, sodium phosphate, sodium lactate, sodium iodide at least two or a mixture of various alkali metal salts, and the alkali metal salt accounts for 1% of the total mass fraction of the additive solution ~3%; The surfactant is one of sodium dodecylbenzenesulfonate and coconut oil diethanolamide or a mixture of the two, and the surfactant accounts for 0.5% to 1% of the total mass fraction of the additive solution; The diluent is one of urea and ammonium bicarbonate or a mixture of the two, and the diluent accounts for 0.5% to 1% of the total mass fraction of the additive solution.