RU2466761C1 - Method of forming fire barrier and fire barrier - Google Patents

Abstract

FIELD: fire protection.

SUBSTANCE: method includes operations in which in case of fire, a flexible fire-proof screen is lowered. The screen is made of a material with a capillary-porous structure for closing the opening of the protected movement. The coolant is supplied into the flexible fire-proof screen to create in its capillary structure of steam-drop-air environment. The coolant is supplied so that at the initial stage the coolant penetrates into the wall of the screen by capillary phenomena, and then, going deep into the distance equal to the height of the capillary rise of the liquid spreads down the screen by filtering effect under the action of its gravity. The flow of coolant is regulated so that the temperature at any point on the unheated surface of the fire-proof screen is equal to the temperature of water evaporation. The impregnating fire barrier assembly comprises a container placed inside the housing over the opening for passage of the screen neighbouring close by the container forming one of its walls.

EFFECT: increased efficiency of the barrier, lack of unevaporated part of the liquid flowing from the screen, decrease of the liquid flow, the lack of sections of the screen unsoaked with water.

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Description

FIELD OF THE INVENTION

The invention relates to fire fighting equipment and is intended to localize a fire in open technological openings, openings of buildings and structures by forming a fire barrier in which a fire shield is used.

Description of the prior art

The main structural element of fire barriers in the form of curtains, determining their effectiveness, is a fireproof screen. Its main technical characteristics are determined by the design and operation mode, and are also characterized by a normalized fire resistance limit. The fire resistance of a structure is the time interval from the beginning of the fire exposure to the onset of one of its limiting states, which are:

- in case of loss of integrity, the formation of through cracks or holes in the structure through which combustion products or flame penetrate the unheated surface;

- in case of loss of heat-insulating ability, temperature increase on the unheated surface of the structure at any point on this surface by more than 180-220 ° C.

A wide variety of fire protection designs have been proposed that utilize a fire protection screen.

Moreover, the closest analogue of the present invention is a technical solution known from patent FR 2212759, which discloses a fire fighting device, comprising: at least one flexible capillary-porous fire-retardant shield for a liquid, placed in its initial state inside the housing located in the region, which must be protected from fire; means for lowering the fire shield in case of fire; an impregnating assembly provided inside the housing for impregnating the fire shield with coolant when it is unwound and lowering down, as well as for continuously impregnating the screen after lowering it. Impregnation is carried out by means of sprays made inside the housing. In one embodiment, said impregnation unit includes a container located inside the housing, configured to accumulate coolant therein, draining, as a result of spraying, from the impregnated screen wound on a winding shaft.

This design eliminates the disadvantages characteristic of solutions in which the unheated surface of the screen is irrigated with liquid supplied from sprayers located above the opening at some distance from the screen plane. Since in the patent FR 2212759, the spraying is carried out inside the housing, the water consumption is slightly reduced and the need for laying pipes and sprayers outside the fire barrier is eliminated.

However, this design has, in particular, the following disadvantages:

- although the sprayers are located near the screen, the spraying method is still used and, therefore, the formation of a significant amount of an unevaporated part of the water is inevitable, which has a destructive effect on the building structures, decoration and furnishings of the protected premises;

- in addition, the design of the impregnation unit does not guarantee 100% coverage of the screen with water, especially when it is bent, caused by excessive pressure in the room in which a fire occurs.

Disclosure of invention

The technical problems of the proposed solution are those that ensure the elimination or at least reduction of the influence of these problems of the prior art and, in particular: the absence of an unevaporated part of the liquid leaking from the screen; reduction of water consumption and pressure requirements in the water supply; preservation for some time of the insulating ability of the screen; as well as the absence of sections of the screen not soaked with water when it is bent, caused by excessive pressure in the fire room.

The tasks are solved in the proposed method of forming a fire barrier, in which:

when a fire occurs, lower the flexible fireproof screen made of a material with a capillary structure to block the opening of the protected movement;

coolant is supplied into a flexible fireproof screen to create a vapor-droplet-air medium in its capillary structure, while coolant is supplied so that at the initial stage the coolant penetrates the wall of the screen by means of capillary phenomena and then, going deeper into the distance equal to the height of the capillary rise liquid spreading down the screen through the phenomenon of filtration under the influence of its gravity; and

after that, the coolant flow rate is controlled in such a way that the temperature at any point on the unheated surface of the fire shield is equal to the temperature of water evaporation.

The regulation of the flow rate of the coolant is preferably carried out by changing the flow area of the fluid supply channel and / or pressure in the fluid supply system in front of said fluid supply channel.

Also, coolant flow rate control can be carried out by creating a capillary-porous medium with specified parameters.

To create a capillary-porous medium with the specified parameters, the fire-resistant screen is preferably made of nonwoven materials based on glass, basalt or silica fibers located between layers of silica fabric with a surface density of 150-600 kg / m ² .

It is possible to alternate layers of different materials and / or a combination in the layer of different fibers of different chemical composition and / or different sizes.

The regulation of fluid flow is preferably carried out automatically by the signal of temperature sensors located in the lower part of the unheated surface of the fireproof screen.

The temperature in the fire retardant screen is preferably maintained in the range of 100-160 ° C.

The present invention also relates to a fire barrier comprising:

a flexible fireproof screen made of a material with a capillary-porous structure and placed in the initial state inside the housing located in the upper area protected from the fire of the protected room and having a passage for the screen in its lower part;

means for lowering the fire shield in case of fire;

an impregnating assembly provided inside the housing for impregnating the fire-retardant shield with coolant when it is unwound and lowering down, as well as for continuously impregnating the shield after lowering it, wherein said impregnating assembly includes a container located inside the housing above said opening for passage of the screen and made with the possibility of supplying coolant to it, moreover, the fireproof screen is adjacent to the container, forming one of its walls.

Fireproof screen can be placed in the housing on the winding shaft or in the folded state.

The container may be closed on top or open on top.

The fire barrier preferably comprises means for controlling the flow of coolant.

The technical result from the implementation of the proposed technical solution is:

- the absence of the non-evaporated part of the liquid leaking from the screen, capable of exerting a destructive effect on building structures, decoration and the environment of protected premises;

- reducing fluid flow and reducing pressure requirements in the water supply in buildings and structures (in large-volume buildings with large openings there is no need for water storage facilities and pumping stations);

- lack of penetration of steam into the protected room;

- preservation for some time of heat-insulating ability upon termination of irrigation of the screen with liquid;

- the absence of sections of the screen not soaked with water, in particular when it is bent, caused by excessive pressure in the fire room.

Brief Description of the Drawings

The invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

Figure 1 - Structural diagram of a fire barrier in the first embodiment;

Figure 2 - Structural diagram of a fire barrier in the second embodiment;

Figure 3 - Calculation scheme of heat and mass transfer in a water-containing capillary-porous structure of a fire-resistant screen in the mode of continuous supply of coolant.

Embodiments of the invention

Below with reference to these figures will be explained the proposed method of forming a fire barrier, as well as the design of such a barrier.

Figure 1 shows a structural diagram of a fire barrier in accordance with the first embodiment, where the reference numbers indicate: 1 - wall; 2 - case; 3 - winding shaft; 4 - capacity of the impregnating unit; 5 - input fitting; 6 - fireproof screen; 7 - heat sealing tape; 8 - a directing roller; 9 - brackets.

In the initial position, in the normal operation mode of the building, the fireproof screen 6 is stored on the winding shaft 3 located inside the housing 2. In case of fire, by the signal from the fire detectors, the fireproof screen 6 is transferred to the working position, thus forming a fire barrier . The deployment of the fireproof screen 6 is carried out, after removing the electromagnetic lock, under the action of its own weight and the weight of the cut-off bus (not shown).

The proposed method involves the manufacture of a fireproof screen 6 from capillary-porous materials and the creation of a vapor-droplet-air medium from a cooling liquid in its porous wall. This allows you to realize the maximum number of mechanisms for removing heat from the heating medium from the screen from the screen.

To supply coolant to the wall of the fireproof screen 6, the ability of a capillary-porous medium to absorb liquid under the action of capillary forces and the ability to organize its flow in the pores, described in the scientific and technical literature as a filtering phenomenon, are used.

As shown in figure 1, the fireproof screen 6 in the initial state on the winding shaft 3 is stored inside the housing 2, which is installed above the opening in the walls 1 and partitions, on the ceiling or other structures of the supporting frame of the building.

In an alternative design, the fireproof screen 6 may be stored inside the housing 2 in a folded state (not shown) according to the accordion principle.

In case of fire (in automatic mode at the signal of the detectors or in manual mode), the fireproof screen 6 is lowered by gravity and, thus, a fire barrier is formed. The lowering depth is usually equal to the height of the opening or corridor. In the lower part of the screen 6, a cut-off tire (not shown) is mechanically fixed, which has sufficient mass for the rapid lowering of the fire-retardant screen, and also makes it close to the floor or lower part of the opening.

When the temperature of the unheated surface of the fireproof shield 6 increases to a critical value, coolant (water) begins to be supplied to it. The critical value of the temperature should be determined as the difference between the value corresponding to the loss of heat-insulating ability, and the magnitude of its change in the period of time from the moment the liquid was introduced into the container 4 until the liquid saturates the bottom of the screen 6.

Coolant is supplied from the water supply line to the tank 4 through the nozzle 5, forming an impregnating unit. The flow rate of the supplied coolant is determined by the size of the cross-section in the nozzle 5 and the pressure in the system in front of it, which in one embodiment comprise means for controlling the flow rate of the coolant.

In accordance with the invention, the screen 6 is adjacent to the container 4, forming one of its walls. An additional attraction of the screen 6 to the tank 4 is carried out by means of a guide roller 8, which in this embodiment is located in the upper part of the tank 4. This fit of the screen 6 to the tank 4 is an important distinguishing feature of the proposed solution, which provides the specified technical result. Due to the fact that the screen 6 is in constant contact with the volume of coolant contained in the tank 4, i.e. actually immersed in it, at the initial stage, the coolant penetrates the screen 6 by means of capillary phenomena and, having reached a distance equal to the height of the capillary rise of the liquid, spreads down the screen 6 through the phenomenon of filtration under the action of its own gravity.

It should be noted that since the fire shield 6 is heated to a temperature higher than the boiling point of the coolant at the initial stage of coolant supply, a reactive force can arise when the coolant evaporates, preventing its penetration into the web. In the design of the impregnation unit, this situation is taken into account as follows.

If there is an obstacle to the penetration of the coolant into the fireproof screen 6, further filling of the container 4 will be carried out. Full filling of the tank 4 with cooling liquid will increase the pressure in it. As a result, a force appears, revealing the lower joint between the screen 3 and the edge of the container 4, while there is an instant spill of water on the surface of the screen 6 through the gap formed and, as a result, its saturation in a minimum time.

To prevent the spread of flame from the room where the fire broke out, into the protected room, in the passage for the screen 6, made in the lower part of the housing 2, as well as in the guide rods, in which a similar passage is organized, the heat-sealing tape 7. The heat-sealing tape 7 is able to expand at temperatures above 200 ° C, filling the free space in the passage for the screen 6. It is noteworthy that this occurs at a higher temperature than with the initial saturation of the fire shield 6 coolant th. Thus, the initial saturation of the fire-retardant screen 6 with a cooling liquid occurs unhindered.

After eliminating the fire, the fire barrier is returned to its original position by winding the fire shield 6 onto the winding shaft 3. In this case, the rotation of the shaft 3 is carried out using a tubular motor.

Figure 2 shows an alternative embodiment of the impregnating unit. Moreover, in this figure, structural elements corresponding to similar elements of the first embodiment are denoted by the same reference positions.

According to this option, the tank 4 for coolant is not closed, and therefore, at the initial stage of saturation of the fire shield 6, overflow of the tank 4 and overflow of coolant to the lower part of the housing 2, from where it enters the fire shield 6 through openings 10 in the passage passage for the screen, made in the housing 2.

The constructive implementation of the guide elements represented by guide rods and locking rollers fixed on the lateral edges of the fire barrier, as well as the contact area of the fire shield 6 to the floor or the lower part of the opening with the use of a cut-off tire, can be performed similarly to traditional designs.

Another important distinguishing feature of the proposed solution is the regulation of the flow rate of the coolant, which is done by creating a capillary-porous medium with the given parameters and / or using the means for regulating the flow rate of the coolant (not shown), which changes the flow rate of the water when it is supplied to the impregnating unit .

To create a capillary-porous medium non-woven roll materials based on glass, basalt or silica fibers are used, located between layers of silica fabric with a surface density of 150-600 kg / m ² . Layers can be fastened together by a transverse stitch. It is possible as the alternation of layers of various materials, and a combination of different fibers in the layer. In addition, a combination in the layer of fibers of different chemical composition and different sizes is possible.

The combination of the intermediate layers and the composition of the fibers within each layer is selected according to optimization criteria by the calculation method developed on the basis of a mathematical model of heat and mass transfer in the wall of the fireproof screen, corresponding to the operating conditions of the fire barrier in case of fire. The following is a mathematical model and optimization criteria of the proposed technical solution.

The flow rate control of the liquid supplied to the impregnation unit (this is especially true at the initial stage of the fire, when the operating temperature changes significantly over time) can be carried out automatically by the signal of temperature sensors located at the bottom of the unheated surface of the fireproof screen. In this zone, the temperature should be maintained in the range of 100-160 ° C. The proximity of the approximation should be determined experimentally. Lowering the temperature to less than 100 ° C is an indirect sign of leakage of coolant from the screen. An increase in temperature to values exceeding 160 ° C indicates a local loss of heat-insulating ability. The regulation of the flow of coolant in this case is carried out by opening / closing the damper installed at the inlet to the nozzle 5 (Fig.1 - 2). Coolant flow rate control is carried out in such a way that the temperature at any point on the unheated surface of the fire shield is equal to the temperature of water evaporation.

The effectiveness of the proposed technical solution is justified by mathematical modeling of heat and mass transfer processes in a water-containing wall of a fire-resistant screen in case of fire.

The mathematical model is constructed with assumptions that simplify the solution of heat and mass transfer equations, but preserve the defining physical phenomena.

When modeling heat and mass transfer processes, we consider a two-dimensional region bounded by the transverse coordinate ξ by the surfaces of the screen, and by the longitudinal coordinate η, the base and height of the screen. Figure 3 shows the design scheme of heat and mass transfer in the water-containing capillary-porous wall of the fire-resistant screen in the continuous supply of coolant, which are indicated on: I - zone of dry material; II-evaporation front; III - zone of water-containing material.

- массовая скорость испарения охлаждающей жидкости; ξ_d - координата фронта испарения; T_w - температура обогреваемой поверхности; Т_v - температура испарения; T_f - температура пламени; α_f - коэффициент конвективной теплоотдачи от продуктов горения к омываемой ими поверхности экрана; ε_f - излучательная способность пламени;

- массовая скорость течения охлаждающей жидкости; η_a - координата границы зоны с адсорбционной жидкостью; т_а - время достижения границы зоны с адсорбционной жидкостью координаты η_a; w - массовое содержание охлаждающей жидкости; δ - толщина экрана; Δη - размер элементарного слоя по координате η; Δξ_d - уменьшение проходного сечения для потока охлаждающей жидкости по толщине слоя Δη.In addition, figure 3 uses the following notation: q _w is the density of the heat flux absorbed by the heated surface of the screen;

- mass rate of evaporation of the coolant; ξ _d is the coordinate of the evaporation front; T _w - temperature of the heated surface; T _v - evaporation temperature; T _f - flame temperature; α _f is the coefficient of convective heat transfer from the combustion products to the screen surface washed by them; ε _f is the emissivity of the flame;

- mass flow rate of the coolant; η _a is the coordinate of the boundary of the zone with the adsorption liquid; t _a - time to reach the boundary of the zone with the adsorption liquid of the coordinate η _a ; w is the mass content of the coolant; δ is the thickness of the screen; Δη is the size of the elementary layer along the coordinate η; Δξ _d is the decrease in the flow cross section for the flow of coolant along the layer thickness Δη.

The fire-resistant screen is exposed to a one-sided fire effect, which is characterized by the direct contact of the flame with the heated surface.

и стекает вниз по порам под действием силы тяжести. Одновременно происходит испарение жидкости, сопровождающееся массопереносом пара в капиллярно-пористой среде стенки в направлении к обогреваемой поверхности. В результате этого образуются две характерные зоны: сухого и водосодержащего материала, на границе которых происходит испарение жидкости. Водосодержащий материал характеризуется массовым содержанием жидкости w.Coolant is supplied to the upper part of the screen wall with mass velocity

and flows down the pores by gravity. At the same time, evaporation of the liquid occurs, accompanied by mass transfer of vapor in the capillary-porous wall medium in the direction of the heated surface. As a result of this, two characteristic zones are formed: dry and water-containing material, at the boundary of which liquid evaporation occurs. The water-containing material is characterized by a mass liquid content w.

The physical processes taking place in a fireproof screen are described by the equations of heat transfer and mass balance. The result of their joint solution is the distribution of the thickness of the dry layer along the height of the screen for the equilibrium state of the process. In this state, the liquid expended on evaporation is compensated by its inflow from the outside, and the distribution of the thickness of the dry layer along the height of the screen is stationary.

Mass transfer of coolant in the wall of the fire-resistant screen is the result of two main processes: filtration under the action of gravity and capillary lifting, due to the phenomenon of wetting and surface tension of the liquid. Within the framework of the developed mathematical model, it is described by the expression for the mass velocity of the fluid obtained on the basis of the Darcy formula and the expression for determining the height of the capillary rise of the fluid in the form:

- массовый расход жидкости; k_p - коэффициент проницаемости, µ - динамическая вязкость жидкости, ρ_W - плотность жидкости; h_k - высота капиллярного поднятия жидкости; ρ₀ - плотность сухого материала стенки экрана; Н - высота экрана.Where

- mass flow rate of liquid; k _p is the permeability coefficient, µ is the dynamic viscosity of the fluid, ρ _W is the density of the fluid; h _k is the height of the capillary rise of the liquid; ρ ₀ is the density of the dry material of the screen wall; H is the height of the screen.

A controlled parameter that affects fluid flow is the permeability coefficient.

It should be noted that the permeability coefficient is a complex indicator that depends on the chemical nature of the material and its macrostructure. It is advisable to determine this indicator experimentally for each specific material.

According to the Kozeny-Karman hypothesis, the permeability coefficient is determined by the parameters of the capillary-porous structure of the screen wall materials in accordance with an expression of the form:

where S _f is the specific surface of the fibers; k is a structural factor.

Thus, to obtain the required flow rate of the fluid flowing inside the screen, the main variable parameters can be: porosity of the screen material, fiber diameter, and also the viscosity of the fluid supplied to the screen.

When the diameter range of the fibers forming the materials used in the structure of the screen wall is 1-15 μm, the permeability coefficient can vary over a wide range.

The distribution of the thickness of the dry layer along the height of the screen is optimal when all the liquid supplied to its wall is spent on evaporation and does not flow into the surrounding space from the bottom of the screen. Moreover, the temperature at any point located on the unheated surface of the screen should be equal to the temperature of evaporation of water, that is, 100 ° C. This is ensured by the fulfillment of the condition for equality of the thickness of the dry layer in the extreme lower value of the ordinate of the thickness of the screen.

The calculations carried out within the framework of the developed mathematical model also show a significant reduction in the flow rate of liquid supplied to the screen in comparison with the known designs of fire barriers. Minimum values may be about 0.005 l / m ² .

The above options for the implementation of fire barriers should be considered only as exemplary options. Various modifications of the above described design options are also possible, which will also be apparent to those skilled in the art. It is intended that such embodiments do not limit the proposed solution, the scope of which is determined by the following claims.

Claims (12)

1. The method of forming a fire barrier, in which:
when a fire occurs, lower the flexible fireproof screen made of a material with a capillary-porous structure to block the opening of the protected movement;
coolant is supplied into a flexible fireproof screen to create a vapor-droplet-air medium in its capillary structure, while the coolant is supplied so that at the initial stage the coolant penetrates the screen wall by means of capillary phenomena and then, going deeper into the distance equal to the height capillary rise of the liquid, spreading down the screen through the phenomenon of filtration under the action of its gravity; and
after that, the coolant flow rate is controlled in such a way that the temperature at any point on the unheated surface of the fire shield is equal to the temperature of water evaporation. 2. The method according to claim 1, in which the regulation of the flow rate of the coolant is carried out by changing the flow area of the fluid supply channel and / or pressure in the fluid supply system in front of the specified fluid supply channel. 3. The method according to claim 1, in which the regulation of the flow rate of the coolant is carried out by creating a capillary-porous medium with predetermined parameters. 4. The method according to claim 3, in which to create a capillary-porous medium with specified parameters, a fire-resistant screen is made of non-woven materials based on glass, basalt or silica fibers located between layers of silica fabric with a surface density of 150-600 kg / m ² . 5. The method according to claim 4, in which the alternation of layers of various materials and / or a combination in the layer of different fibers of different chemical composition and / or different sizes. 6. The method according to claim 4, in which the regulation of the flow rate of the coolant is carried out automatically by the signal of temperature sensors located at the bottom of the unheated surface of the fire shield. 7. The method according to claim 1, in which the temperature in the fireproof screen is maintained in the range of 100-160 ° C. 8. A fire barrier containing:
a flexible fireproof screen made of a material with a capillary-porous structure and placed in the initial state inside the housing located in the upper area of the room protected from fire and having a passage for the screen in its lower part;
means for lowering the fire shield in case of fire; and
an impregnating assembly provided inside the housing for impregnating the fire-retardant shield with coolant when it is lowered down, as well as for continuously impregnating the shield after lowering it, where said impregnating assembly includes a container located inside the housing above said opening for passage of the screen and configured to supply coolant in it, and the fire-retardant screen is adjacent to the container, forming one of its walls. 9. The fire barrier of claim 8, in which the fireproof screen is placed in the housing on the winding shaft or in the folded state. 10. Fire barrier according to claim 8, in which the container is made closed from above. 11. Fire barrier according to claim 8, in which the tank is made open at the top. 12. Fire barrier according to any one of paragraphs.8-11, further comprising means for regulating the flow of coolant.

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