RU2242260C1 - Low-expansion foam generator for sublayer fire-extinguishing in tank - Google Patents

Abstract

FIELD: equipment for fire-extinguishing low-expansion foam preparation, particularly for extinguishing fire in tank with oil, oil products or other inflammable liquids.

SUBSTANCE: foam generator comprises body with nozzle-like channel for ejecting aqueous foam-generation solution into body and with gas injection orifice, mixing chamber installed in the body so that inlet orifice thereof is located opposite to nozzle. Foam generator also has diffuser adjoining mixing chamber at its outlet. Mixing chamber is installed opposite to at least two nozzles having summary area of outlet cross-sections thereof corresponding to predetermined flow rate of aqueous foam-generation solution.

EFFECT: increased efficiency due to increasing foam expansion ratio up to 3, possibility of stable foam generation under pressure of 0.9±0.1 MPa due to change in configuration of nozzle for supplying aqueous foam-generation solution.

4 cl, 6 dwg

Description

The invention relates to the field of fire extinguishing, in particular to devices for the preparation of low-foam foam and can be used for sub-layer fire fighting in a tank with oil, oil products or other flammable liquid, in which a foam with a multiplicity of at least 3 is introduced under a layer of burning liquid in a tank with subsequent spontaneous rise and spreading of foam on the surface of a burning liquid.

A well-known low-foam foam generator for sub-layer fire fighting in a tank described in the Prospectus for high-pressure mod K foam generators from KS Anticendendi, Italy, 1998. This generator, like the claimed one, contains a housing, a nozzle for supplying an aqueous solution of a foaming agent, an opening in the case for supplying (sucking) gas, a mixing chamber mounted by an inlet opposite the nozzle, and a diffuser connected to the mixing chamber at its outlet. The nozzle is configured to supply one jet of an aqueous foaming agent solution. The disadvantage of this low-foam generator is the relatively unstable production of foam with a multiplicity of at least 3, especially at the working pressure (pressure in front of the generator) of an aqueous foaming agent solution of 0.9 ± 0.1 MPa. The values of the foam multiplicity of not less than 3 and the working pressure of 0.9 ± 0.1 MPa are established by the Fire Safety Standards NPB 61-97 “Fire fighting equipment. Foam fire extinguishing installations. Foam generators of low multiplicity for sublayer extinguishing of tanks. General requirements. Test methods. The official publication. The Ministry of the Interior of the Russian Federation. State fire service. Moscow. 1997 ”

A well-known low-foam foam generator, the information on which is contained in the description of the patent of the Russian Federation for invention No. 2145680, F 04 F 5 \ 02, publication 02/20/2000, bulletin No. 5 and in Technical conditions 1021.25.009.00.00.000 TU “High-pressure foam generators of low-level foam for the fire extinguishing system VPG-10 \ 20 \ 30 ”, AK Transneft, TsentrSibnefteprovod OJSC, TOMZEL CJSC, 1998. The generator contains a cylindrical body with flanges at the ends, one of which has a nozzle for supplying water foaming agent solution. In the side surface of the housing is a radial gas supply pipe.

Inside the casing opposite the nozzle, a cylindrical mixing chamber with expansion at the inlet is installed, and then there is a cone-shaped diffuser at the outlet of the mixing chamber. The nozzle is configured to supply one jet of an aqueous foaming agent solution.

This invention is taken as a prototype.

The disadvantage of the prototype generator is the low foam ratio that does not meet the Fire Safety Standards of NPB 61-97, according to which it must be at least 3 at a working pressure of 0.9 ± 0.1 MPa.

The objective of the invention is to increase the efficiency of the low-foam generator. The technical result is expressed in an increase in the multiplicity of the foam to a value of at least 3 according to Fire Safety Standards NPB 61-97 and its stable production at a working pressure of the flow of the foaming agent solution of 0.9 ± 0.1 MPa due to a change in the design of the nozzle for supplying an aqueous solution of the foaming agent.

Like the prototype, the low-level foam generator for sub-layer fire fighting in the tank contains a housing with an opening in the form of a nozzle for supplying an aqueous solution of a foaming agent to the housing and with an opening for supplying gas, a mixing chamber installed in the housing with an inlet opening opposite the nozzle, a diffuser adjacent to the mixing chamber at her exit.

In contrast to the prototype, the mixing chamber is installed opposite at least two nozzles, the total area of the output cross sections of which corresponds to a given flow rate of an aqueous solution of a foaming agent.

At least one nozzle may be opposite the central part of the inlet of the mixing chamber, and at least two nozzles opposite its periphery, all nozzles being symmetrically relative to the longitudinal axis of the mixing chamber.

On the inner surface of at least one nozzle located opposite the central part of the inlet of the mixing chamber, there may be a helical groove.

At least one nozzle located opposite the periphery of the inlet of the mixing chamber can be configured to direct the flow of the foaming agent aqueous solution at an angle α = 1: 5 degrees to the longitudinal axis of the mixing chamber.

The low-foam generator is shown in figures 1-6.

The figure 1 shows: 1 - casing, 2 - nozzles, 3 - hole for gas supply, 4 - mixing chamber, 5 - inlet of the mixing chamber 4, 6 - diffuser.

The figure 2 shows: 7 - nozzle located opposite the Central part of the inlet 5 of the mixing chamber 4, 8 - nozzle located opposite the periphery of the inlet 5 of the mixing chamber 4.

The figure 3 shows the nozzle 7 with a helical groove 9.

The figure 4 shows the implementation of the nozzle 8 with the possibility of directing the flow of an aqueous solution of the foaming agent at an angle α = 1: 5 degrees to the longitudinal axis of the mixing chamber 4.

Figures 5 and 6 illustrate examples of a specific embodiment of a generator with a different number and arrangement of nozzles 7 and 8 relative to each other.

In the housing 1 (Fig. 1) there are openings in the form of at least two nozzles 2 for supplying an foaming agent aqueous solution to the housing and an opening 3 for supplying gas. The mixing chamber 4 is installed so that its inlet 5 is located in the housing 1 opposite the nozzles 2. The inlet 5 of the mixing chamber 4 can be round in cross section, as well as made in the form of a rectangular, elliptical and other slit. A diffuser 6 is adjacent to the mixing chamber 4 at its output. The total area of the outlet cross sections of the nozzles 2 corresponds to a predetermined flow rate of the foaming agent aqueous solution.

Opposite the central part of the inlet 5 of the mixing chamber 4, there can be at least one nozzle 7, and opposite its periphery at least two nozzles 8 (FIG. 2). All nozzles 7 and 8 are located symmetrically relative to the longitudinal axis of the mixing chamber 4.

At least one nozzle 7, located opposite the Central part of the inlet 5 of the mixing chamber 4, may have a helical groove 9 on its inner surface (figure 3). The helical groove 9 may be in the cross section of a rectangular, square, triangular, semicircular, or any other. The inclination of the helical line along which the helical groove 9 is located is selected with the possibility of ensuring the twisting of the jet of the foaming agent escaping from the nozzle 7.

At least one nozzle 8, located opposite the periphery of the inlet 5 of the mixing chamber 4, is configured such that the flow of the foaming agent aqueous solution is directed at an angle α = 1: 5 degrees to the longitudinal axis of the mixing chamber 4 (FIG. 4). The angle α can be achieved by installing the nozzles 8 or by bending the nozzle channel 8 at this angle to the longitudinal axis of the mixing chamber 4. Moreover, the nozzle 7, located opposite the central part of the inlet 5 of the mixing chamber 4, can be like a screw groove 9, so without it.

Nozzles 2, including nozzles 7, located opposite the central part of the inlet 5 of the mixing chamber 4, and nozzles 8, located opposite the periphery of the inlet 5 of the mixing chamber 4, can be of any configuration that would provide the necessary acceleration and direction of the aqueous solution of the foaming agent.

The device operates as follows. An aqueous solution of the foaming agent is fed into the housing 1 through the nozzle 2 (figure 1). The jets of the foaming agent aqueous solution from the nozzles 2 entrain the gas coming from the opening 3 into the mixing chamber 4. In the mixing chamber 4, a low-level foam is formed. From the mixing chamber 4, the low-foam foam flow enters the diffuser 6, where it is inhibited and the low-foam foam flow pressure increases to a value greater than the back pressure of the burning liquid layer. From the diffuser 6, the foam stream exits, for example, into a foam conduit (not shown), and then enters the reservoir (not shown) below the surface of the burning liquid, under its layer and then rises up to the surface of the burning liquid and spreads along it, which leads to quenching fire.

Thus, in the mixing chamber 4 serves several jets of an aqueous solution of a foaming agent instead of one jet, as in the prototype, by placing opposite the inlet 5 of the mixing chamber 4 several nozzles 2, the total area of the output cross sections corresponding to a given flow rate of the aqueous solution of the foam, instead of one nozzles, as in the prototype.

In the inventive low-foam generator, the amount of gas captured by the surface of the jets is increased compared to the prototype due to an increase in their total surface compared to the surface of one jet in the prototype. In addition, when 4 jets of an aqueous solution of the foaming agent are fed into the mixing chamber, the process of mixing it with gas is intensified, which leads to the stability of obtaining a low-level foam.

When distributing the nozzles 7 in the center and the nozzles 8 on the periphery opposite the inlet 5 of the mixing chamber 4 symmetrically with respect to the longitudinal axis of the mixing chamber 4, an additional increase in the foam multiplicity occurs due to the creation of a uniform gas space inside the flow, which helps to increase the multiplicity.

For example, when supplying an aqueous solution of a foaming agent through twelve nozzles located next to each other in a low-foam foam generator operating with a capacity of 30 l / s and a working pressure of an aqueous solution of a foaming agent of 0.8 MPa, the foam multiplicity was 3.01, and when supplying an aqueous the foaming agent through twelve nozzles, three of which are located opposite the central part of the inlet 5 of the mixing chamber 4 (nozzle 7) and nine are opposite its periphery (nozzle 8) (Fig. 5), the foam multiplicity was 3.14. That is, the multiplicity increased by 4.3%.

The helical groove 9, at least on one nozzle 7, located opposite the central part of the inlet 5 of the mixing chamber 4, ensures the twisting of the jet of the foaming agent water, its divergence to the walls of the mixing chamber 4 and increases the intensity of the turbulent pulsations of the jet. Turbulent pulsations of the jet (or several jets) exiting the nozzle (or exiting several nozzles) opposite the central part of the outlet 5 of the mixing chamber 4 intensify the process of mixing the aqueous solution of the foaming agent with gas. Large vortices formed in the central zone of the flow of the foaming agent aqueous solution transfer their energy to the peripheral part of the flow, which further contributes to the mixing of the flow of the foaming agent aqueous solution with gas and the stable production of foam, with a multiplicity of at least 3 according to NPB 61-97.

The implementation of at least one nozzle 8, located opposite the periphery of the outlet 5 of the mixing chamber 4, with the possibility of directing the aqueous solution of the foaming agent at an angle α = 1: 5 degrees to the longitudinal axis of the mixing chamber 4 ensures that its flow crosses with the flow from another nozzle 7 or (i) 8, their collision and, consequently, the best mixing of the aqueous solution of the foaming agent with gas, which leads to an additional increase in the multiplicity of the foam and increase the stability of the production of foam, the multiplicity of not less than 3 according to NPB 61-97, and also, in the case of one or more nozzles 7 with a screw groove 9, prevents a significant expansion of the swirling central jet.

The interval of the angle α of the direction of the foaming agent aqueous solution to the longitudinal axis of the mixing chamber 4 is selected within 1: 5 degrees based on the fact that at an angle of less than one degree there is no significant crossing and mixing of the flows and, consequently, an additional increase in the multiplicity, and at a larger angle, than 5 degrees, there is a significant loss of energy in the flow of an aqueous solution of a foaming agent.

Examples of specific versions of the generator with different numbers and arrangement of nozzles 7 and 8 relative to each other.

Example 1. The low-foam generator contains a housing 1 with holes in the form of six nozzles (Fig.6) for supplying an aqueous solution of a foaming agent to the housing 1. In this case, one nozzle 7 is located opposite the central part of the inlet 5 of the mixing chamber 4, and five nozzles 8 are opposite its periphery. The nozzles 7 and 8 are located symmetrically with respect to the longitudinal axis of the mixing chamber 4. The generator capacity (flow rate of the foaming agent aqueous solution) is 10 l / s. This performance corresponds to the total area of the output cross sections of the nozzles 7 and 8.

The generator is supplied with an aqueous solution of a foaming agent with a working pressure of 0.8 MPa, and a low-level foam is obtained at its output.

In the inventive generator with six nozzles compared with the prototype, having one nozzle and working with the same performance and working pressure, the foam ratio increased by 29% and amounted to 3.63, which corresponds to fire safety standards 61-97. At the same time, the prototype foam multiplicity was 2.81, which is below the norms of the airbag 61-97.

Example 2. The low-foam generator contains a housing 1 with holes in the form of twelve nozzles (Fig. 5) for supplying an aqueous solution of a foaming agent to the housing. In this case, three nozzles 7 are located opposite the central part of the inlet 5 of the mixing chamber 4, and nine nozzles 8 are opposite its periphery. The nozzles 7 and 8 are located symmetrically with respect to the longitudinal axis of the mixing chamber 4. The generator capacity (flow rate of the foaming agent aqueous solution) is 30 l / s. This productivity corresponds to the total area of the output cross sections of the nozzles 7 and 8. An aqueous foaming agent solution with a working pressure of 0.8 MPa is supplied to the generator and a low-level foam is obtained at its output.

In the inventive generator having twelve nozzles, the foam ratio increased by 6.8% compared with the prototype and amounted to 3.14, which corresponds to the fire safety standards of airbags 61-97. The multiplicity of the foam in the prototype, having one nozzle and providing the same productivity of 30 l / s at the same working pressure of 0.8 MPa, was 2.94, which is below the norms of the airbag 61-97.

Thus, in the inventive low-foam generator, an increase in the efficiency of its work was achieved with an increase in the multiplicity and stability of the production of foam with a multiplicity of at least 3.

Claims (4)

1. A low-level foam generator for sub-layer fire fighting in a tank, comprising a housing with an opening in the form of a nozzle for supplying an aqueous solution of a foaming agent to the housing and with an opening for supplying gas, a mixing chamber installed in the housing with an inlet opening opposite the nozzle, a diffuser adjacent to the mixing chamber on its output, characterized in that the mixing chamber is installed opposite at least two nozzles, the total area of the output cross-sections of which corresponds to a given flow rate of an aqueous foam solution ator. 2. The low-foam generator according to claim 1, characterized in that there is at least one nozzle opposite the central part of the inlet of the mixing chamber and two nozzles opposite its periphery, all nozzles being symmetrically relative to the longitudinal axis of the mixing chamber. 3. The low-foam generator according to claim 2, characterized in that on the inner surface of at least one nozzle located opposite the central part of the inlet of the mixing chamber, there is a helical groove. 4. The low-foam generator according to any one of claims 2 and 3, characterized in that at least one nozzle located opposite the periphery of the inlet of the mixing chamber is configured to direct the flow of an aqueous solution of the foaming agent at an angle α = 1: 5 ° to the longitudinal axis of the mixing chamber.

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