JPH11165053A - Mixer for fluid and operation of the mixer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To allow CO2 and foam to act even on a fire-extinguishing nozzle on the downstream side by improving a mixer for supplying CO2 into a fire- extinguishing medium and forming an almost homogeneous two-phase mixture with regulated CO2 and foam. SOLUTION: The longitudinal axis of a casing 1 is directed vertically, a fire-extinguishing medium feed conduit 2 is connected to the lower end of the casing 1, an outlet conduit 5 is branched from the upper end of the casing 1, a CO2 feed pipe 4 is inserted into the casing 1 from the upper side and extended close to the lower end of the casing 1, a jet means 6 is fixed to the pipe end, CO2 is introduced countercurrent into the fire-extinguishing medium from the feed pipe, and the length of the feed pipe between a metering valve 3 and the jet means is so controlled that a gas cushion 7 is formed on the downstreams side of the valve 3 when the valve 3 is closed during the operation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

FIELD OF THE INVENTION The present invention relates to a mixing device for supplying CO ₂ into an advantageously liquid fire extinguishing medium,
Almost casing with fire extinguishing medium supply conduit, the supply tube equipped with a metering valve for CO _2, as well as those of the type made of the outlet conduit. With such a device, a homogeneous bubble stream is formed upstream of the fire-extinguishing nozzle of the fire-extinguishing device.

[0002]

2. Description of the Related Art Such a mixing device is known, for example, from WO 95/24272. In this case, an inert gas, usually provided as a gas, serves as a drive medium for the fire-extinguishing medium. The inert gas is intermittently fed into the mixing device to obtain a defined plug flow in the feed conduit to the firefighting nozzle. Federal Republic of Germany Utility Model U1295109
In known solutions for hand fire extinguisher according to 82 Pat, CO ₂ is supplied to the extinguishing medium in the extinguishing nozzles. In this way, an aerosol-like mixture is formed by water droplets at a freezing temperature. Obviously, it is not possible to form a homogeneous bubble flow upstream of the fire-extinguishing nozzle using such means.

[0003] The object of the invention is to improve a mixing device of the type mentioned at the outset, so that a substantially homogeneous two-phase mixture can be produced with defined CO2.
_2. It is formed by air bubbles (CO ₂ -Blase), so that the CO ₂ air bubbles act on the fire extinguishing nozzle on the downstream side. A further object is to provide a means to adequately prevent icing of extinguishing medium based on the expansion of the CO ₂ liquid.

In order to solve the above-mentioned problem, according to the present invention, the longitudinal axis of the casing is vertically oriented, the extinguishing medium supply conduit is connected to the lower end of the casing, and the outlet conduit is connected to the casing. A supply pipe for CO ₂ penetrating into the casing from above and extending at least approximately to the lower end of the casing, with a jetting means at the pipe end. The CO ₂ is directed countercurrently in the supply pipe to the fire-extinguishing medium, the length of the supply pipe between the metering valve and the injection means being such that the metering valve is closed during operation. Is defined so that a gas cushion can be formed on the downstream side of the metering valve when the valve is in operation.

[0005]

An advantage of the present invention is that the structure of the means is particularly simple. In addition, the device works well at operating pressures less than 12 bar. This means that the entire fire extinguishing system, including the conduits and equipment, can be designed at 16 bar suitable for fire protection.

It is particularly advantageous if the outer wall of the supply tube and / or the inner wall of the casing are provided with three-dimensional means for generating vortices. This allows the formation of large longitudinal vortices, which allow controlled rapid mixing of the flowing material over short distances and with low pressure losses. The advantages of such a vortex generator are found in all respects in a particularly simple construction. Furthermore, the component is usually based on a hollow interior and is used to inject the inert gas into the passage which is passed by the fire-extinguishing medium.

[0007]

BRIEF DESCRIPTION OF THE DRAWINGS The drawings show only those components which are important for an understanding of the invention. The supply device for the inert gas and the fire extinguishing medium (Loeschmittel) or the extinguishing agent, which is provided upstream of the mixing device and the fire-extinguishing nozzle (Loeschduese) which is arranged downstream of the mixing device, are not shown.

The device shown in FIG. 1 has a casing 1, which is arranged vertically, as viewed on the longitudinal axis, which can be, in the simplest case, a metal cylindrical tube. The casing has a commercially available mounting member (not shown) at the lower end.
Is connected to the fire-extinguishing medium supply line 2 via a pipe. Upper end of the casing is penetrated by a supply pipe 4 for the CO ₂ with a metering valve 3, in this case, the metering valve is disposed immediately outside the casing. The CO ₂ connection section 8 is provided upstream of the metering valve. Further, an outlet pipe 5 branches off from the upper end of the casing toward the fire extinguishing nozzle.

In the exemplary embodiment, the CO ₂ supply pipe 4 extends coaxially to the lower casing end. The supply pipe is provided with injection means (Einduesungsmittel) 6 at the lower pipe end,
The injection means consist in the simplest case of holes arranged regularly around the tube. Clearly, in this case,
I want to keep the pipe end closed. The supply pipe has a two-part construction, in which case the part 4a adjacent to the metering valve is made of a material with poor thermal conductivity and the part 4b adjacent to the injection means is a material with good thermal conductivity. Consists of This is based on the following considerations based on the type of operation.

The basis is the following data: 4 to 10 bar water, preferably 6 as fire extinguishing medium
It is used at a pressure of bar and preferably at a temperature of 10 °. A water velocity of approximately 5 m / s in the casing 1 is considered to be advantageous. CO ₂ is used as the inert gas, but of course other water-soluble media are also conceivable. The connection 8 is supplied with liquid CO ₂ via a high-pressure line (not shown) at a pressure of up to 70 bar and a temperature of approximately 30 °. The metering valve serves for the original volume adjustment. At the same time, the metering valve functions as a check valve at the start and end of the operation of the device or at the possible intermittent operation of the device.

When the metering valve 3 is closed, the fire extinguishing medium enters the inside of the supply pipe 4 from the casing 1 via the injection means 6 and rises inside the supply pipe 4. In this case, the fire-extinguishing medium compresses a gas column present in the supply pipe, which at least consists of air at start-up, and moves it relative to the metering valve 3 to form a gas cushion 7. Such a state is shown in FIG. The gas cushion prevents water from contacting the metering valve. As is apparent from this, the supply pipe 4 is formed to form a gas plug (Gaspropfen).
Must not be less than some length. Water does not reach the valve even during the strongest turbulence in the water column,
It must be dimensioned to avoid icing. The turbulence and the risk of freezing
This occurs during a subsequent opening of the metering valve. Liquid C
O ₂ is relaxed substantially 8 bar in the metering valve, reaches a temperature of -45 °. As is evident, contact with the water causes the water to freeze immediately and block the supply line. This inert gas flows into the supply pipe and pushes the fire extinguishing medium column back into the casing via the gas cushion. In this case, CO ₂
Is heated and reaches the triple point, at least partially evaporating. Here is the reason for dividing the supply pipe 4 into two parts. The portion 4a adjacent to the metering valve is preferably made of a poorly conductive plastic, so as to ensure as little heat exchange as possible between the water in the housing and the countercurrent cold liquid inert gas. . In any case, it is avoided that icing occurs in said area inside the casing. In order to promote the heating and vaporization of the inert gas further downstream on the other side, here a material with good thermal conductivity is chosen for the part 4b.

Radial holes or sheaves (siebaehnl
The injection means, which may be an additional part of (ich), is such that when the inert gas is injected into the passage through which the fire-extinguishing medium flows, the gas is already homogeneously distributed into the water with the finest possible gas bubbles. The dimensions are specified as follows. However, the nozzle holes must be considered large enough to ensure that freezing at the openings is avoided.

Even if the above-mentioned double point cannot be reached in the supply pipe 4, the liquid inert gas will in any case be vaporized and dissolved upon contact with warm water. In this case, it is first attempted to dissolve as much gas as possible.
The purpose is to achieve saturation of the mixture.

A defined bubble flow downstream of the injection (Blase
To form the nstroemung), a number of CO ₂ than can be dissolved in the extinguishing medium is introduced into the extinguishing medium. The excess that has not been dissolved is in the form of bubbles.

The mixture tends to vaporize in relation to the respective pressure and temperature. Therefore, the pressure drop (Druckverlust) in the conduit is accompanied by vaporization. Part of the pressure drop is compensated by the outgassing of the dissolved inert gas. Evaporation increases the volume.

By way of example, the following values are raised: Injecting 25 grams of inert gas at a pressure of 7 bar into 1 liter of water at 10 ° C. dissolves 15 grams. 10 grams expand at 7 bar to a volume of 0.8 liter. This gives a total volume of 1.8 liters and a total weight of the mixture of 1025 grams. Thus the mixture is approximately 0.57
It has a specific gravity of kg / liter. This means that the water flow (Was
For serstroemung, this means that the pressure drop in the conduit system to the fire-fighting nozzle is significantly smaller. Advantageously, at least a pressure maintenance in the conduit system is achieved by such novel measures. This means that all firefighting nozzles are loaded at approximately the same firefighting pressure independent of the length of the conduit to each firefighting nozzle.

As a result, the desired uniform distribution of the gas in the water may not be achieved from the very beginning due to the large holes of the injection means 6. In order to provide a solution to this, means for influencing the flow are arranged in the form of vortex generators 9 on the casing wall 21 in the passage to be passed. Such a vortex generator is arranged such that a sufficiently large mixing zone 22 is effective in the casing downstream of the vortex generator.

In FIGS. 2 and 3, a vortex generator (Wirbel-Gene
The rator) consists essentially of three triangular faces which are freely flowing, ie covered by a flow. Surface is 1
One top (Dachflaeche) 10 and two sides (Seitenflaech)
e) 11,13. These surfaces are at a given angle to the flow direction.

The side surface (side wall [Seitenwan
d]) is fixed to the casing wall 21 at a wide side (Laengsseite). The side surface is oriented so as to form a seam at a narrow side (Schmalseite) and form a wedge angle α. Seams are sharp joining edges (scharfe Verbindungskante) 16
And is also perpendicular to the side contacting wall 21. Durchstroemqu
erschnitt) is hardly disturbed by blockade, because the joining edges are sharp. The two sides 11, 13 forming the wedge angle α are symmetrically arranged on both sides of the axis of symmetry 17 with respect to shape, size and direction. The symmetry axis 17 points in the same direction as the passage axis.

The upper surface 10 bears on the same wall 21 with which the side surfaces 11, 13 come into contact, with a significantly flattened edge 15 extending transversely to the wall through which it flows.
The longitudinal edges 12, 14 of the upper surface coincide with the longitudinal edges of the side surfaces projecting into the flow passage. The upper surface extends at an elevation angle β with respect to the wall 21. The longitudinal edges 12 and 14 together with the joining edge 16
Is formed.

In FIG. 2, the connecting edge 16 of the two sides 11, 13 forms the downstream edge of the vortex generator 9. The edge 15 of the upper surface 10 thus extending transversely (quer zur umstroemten Wand 21) with respect to the wall 21 to be flowed
Is the edge initially loaded by the passage flow (Kanalstroemung).

The operation of the vortex generator is as follows: as the flow passes over the edges 12, 14, the flow is converted into a pair of opposing vortices. Vortex axis (Wir
The belachse extends along the axis of the passage flow. The geometry of the vortex generator is chosen so that no backflow area is created during vortex generation.

The number of spirals of the vortex is determined by appropriately selecting the elevation angle β and / or the wedge angle β. By increasing the elevation angle, the vorticity or the number of spirals is increased, and the position of the vortex breakdown (Wirbelaufplatzen: vortex break down)
Move upstream (to the extent desired) into the area of the vortex generator itself. The elevation angle α and the wedge angle β are defined by the structural properties and the process itself depending on the use. The height of the vortex generator, that is, the height of the coupling edge 16, must be adapted.

Normally, the height h of the coupling edge 16 is defined in accordance with the passage height H, and the vortex generated has already reached the following size immediately downstream of the vortex generator: The entire mass or the entire height of the passage section belonging to the vortex generator is filled by the vortex, which results in a uniform distribution in the loaded cross section. Another criterion that affects the ratio h / H to choose is the pressure drop that occurs in the flow along the vortex generator. As the ratio h / H increases, the pressure loss value also increases.

In FIG. 3, contrary to FIG. 2, the sharp connecting edge 16 is at the point where it is initially loaded by the passage flow. The component, the vortex generator, is turned 180 °. As is apparent from the drawing, the direction of the spiral is also changed. The vortex rotates along the top surface and towards the wall where the vortex generator is mounted.

A plurality of vortex generators 9 are arranged circumferentially with or without a space between each other and the casing wall 21
Are located in The height of the vortex generator is approximately 90% of the passage height H. It is also possible to arrange vortex generators of the above type in a plurality of planes of the casing in the axial direction or in a uniform manner.

Of course, the invention is not limited to the embodiment shown. Unlike pure water as a fire-extinguishing medium, water-foam mixtures (Wasser-Schaum-Gemisich) are also conceivable. In addition to CO ₂ as an inert gas, nitrogen or air can also be used. It is also possible to vary the characteristic values of the fire-extinguishing medium and the inert gas significantly. In principle, many CO ₂ is dissolved from the lower the water pressure is high and the water temperature. Other components for generating vortices, different from the illustrated vortex generator, can also be used. In principle, as long as the pressure drop is not too great, all static mixtures (statische
r Mischer) is suitable.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a mixing device according to the present invention.

FIG. 2 is a perspective view of a vortex generator.

FIG. 3 is a perspective view of another embodiment of the vortex generator.

[Description of Signs] 1 casing, 2 fire extinguishing medium supply pipe, 3 metering valve, 4 supply pipe, 5 outlet pipe, 6 injection means, 7 gas cushion, 8 CO ₂ connection part, 9 vortex generator, 10 upper surface, 11 side, 12 edge, 13 side, 14,1
5 edges, 16 joining edges, 17 axes of symmetry, 18 vertices, 21 casing walls, 2
2 mixed area

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Frederik Ebischer Switzerland Routerbach Solothurnstrasse 54 (72) Inventor Manfred Ruswurm Germany Federal Bad Schwarta U Liesebusch 41 a

Claims (6)

[Claims] 1. A mixing device for supplying CO ₂ into a fire-extinguishing medium, comprising a casing (1) with a fire-extinguishing medium supply conduit (2), a metering valve (3) for CO _2. In the type consisting of a supply pipe (4) with an outlet and an outlet conduit (5), the longitudinal axis of the casing (1) is oriented vertically and the fire extinguishing medium supply conduit (2) is located below the casing. is coupled to an end portion of the side outlet conduit (5) and is branched from the upper end of the casing, the supply pipe for the CO ₂ (4) is not penetrated from above into the casing, at least approximately Extending to the lower end of the casing and provided with injection means (6) at the end of the pipe, so that the CO ₂ is guided countercurrently in the supply pipe to the fire-extinguishing medium,
The length of the supply pipe between the metering valve (3) and the injection means (6) is such that the gas cushion (3) is located downstream of the metering valve when the metering valve (3) is closed during operation. 7. A mixing device for a fluid, characterized in that it is defined so that 7) can be formed. 2. The supply pipe is formed in a two-part structure, a part (4a) adjacent to the metering valve is made of a material having poor heat conductivity, and a part (4b) adjacent to the injection means is heated. The mixing device according to claim 1, wherein the mixing device is made of a material having good conductivity. 3. The mixing device according to claim 1, wherein the outer wall of the supply pipe and / or the inner wall of the casing are provided with means for generating vortices. 4. The means for generating vortices is a vortex generator (9), wherein a plurality of vortex generators are arranged next to each other in a direction transverse to the flow direction across the width or around the casing wall (21). The vortex generator (9) has three surfaces extending in the direction of flow and flowing freely, one of the surfaces forming the upper surface (10) and the other two of the surfaces The side surface (11, 13) is formed, and the side surface (1
1, 13) abut on the same wall (21) and form a wedge angle (α) with one another, the upper surface (10) being transverse to the wall (21) through which it flows. Extending edge (15)
, Contacting the same wall that the side abuts, the longitudinal edges (12, 14) of the upper surface coinciding with the longitudinal edges of the side protruding into the flow passage and the wall (21). )
4. The mixing device according to claim 3, wherein the mixing device extends at an elevation angle (?) With respect to the mixing device. 5. The ratio of the height of the vortex generator (h) to the height of the flow passage (H) is such that the generated vortex is the entire partial passage height or vortex generation immediately downstream of the vortex generator. 5. The mixing device according to claim 4, wherein the mixing device is selected to reach the full height of the passage section belonging to the vessel. 6. The method for operating a mixing device according to claim 1, wherein when the metering valve is closed, a fire extinguishing medium flows into the supply pipe via the injection means and is present in the supply pipe. The gas column to be compressed is compressed and moved to form a gas cushion for the metering valve, then the metering valve is opened and the liquid C
The O ₂ flows into the supply pipe and the fire extinguishing medium column is pushed back into the casing, where the CO ₂ is heated and at least partially vaporized in achieving the triple point, and the extinguishing medium More CO ₂ than can be dissolved in
The method of operating a mixing device, characterized in that the mixture is introduced into the fire extinguishing medium by an injection means.