JPS625657B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a nozzle device for spraying a mixed gas or liquid onto a predetermined surface for the purpose of cooling by imparting a large momentum to the mixed gas or liquid.

There are a large number of injectors or nozzles in the above field that are more or less suitable for the intended application. Among these various injectors,
In particular, mention may be made of those consisting of a medium-slender central tube of the Laval type. A plurality of side tubes, which are inclined with respect to the longitudinal axis, open into the diverging portion of this central tube. This type of nozzle has an excellent cooling effect on a hot liquid surface, for example a liquid slag, and can effectively granulate it. In addition, in the gist of the present invention and the description of this specification, "Laval tube" refers to a tube whose upstream portion from the air inlet to the neck is configured in a convergent shape.
The downstream portion from the neck to the distal end refers to a tube configured in a shape that widens at the end.

The invention also relates to a nozzle whose main purpose is to cool hot surfaces under completely different conditions from the point of view of operation and the type of objects to which the cooling fluid is to be sprayed. The object to be cooled may be a roll of a rolling mill, and generally, in order for a rolling roll to be used for a long time, its temperature must be uniformly controlled without creating cracks or changing the quenching state. It won't happen. The object to be cooled may also be a rolled product that leaves the rolling mill at a high temperature. When cooling the rolled product, its strength and uniformity must be controlled so as to give the product a predetermined homogeneous structure. Furthermore, the object to be cooled may be a continuously cast ingot, whose effective cooling makes it possible to increase the withdrawal speed without risking wall failure.

On the other hand, as is well known, hot surfaces that come into contact with oxidizing media (for example air) are rapidly covered with a layer of oxides (scale) which are generally harmful to subsequent working steps. When a cooling jet is applied to this hot surface by means of a nozzle, a thermal shock is generated under the action of which the oxide layer is divided, thus making it easier to remove it. This point also constitutes one of the objects of the present invention.

By using a nozzle such as the one described above, it is possible to generate a mist made up of fine water droplets suspended in the air, and then this mist can be sprayed at high speed onto the wall of the object to be cooled.

The nozzle to which the present invention is directed has the advantage of a very large cooling capacity despite its small size (its maximum dimension is generally less than 20 mm). Furthermore, the nozzle allows its cooling capacity to be varied over a very wide range while maintaining good uniformity.

Compared to the cooling capacity of nozzles conventionally used to cool objects whose surface to be cooled has a temperature of 1000°C to 1500°C, the cooling capacity of the nozzle of the present invention is at least twice that, and the cooling effect is also extremely uniform. .

The nozzle which is the object of the present invention has a central tube having a longitudinal cross-sectional shape similar to that of a Laval tube and a neck diameter of 0.7 mm to 2 mm, and an opening into the central tube at the end or outlet of the divergent part of the central tube. and at least one side pipe having an angle of inclination of at least one side pipe, the axis of entry of the side pipe into the central pipe being inclined with respect to the longitudinal axis of the central pipe in the direction of fluid flow; The angle is preferably at least 30°, more preferably about 45°.

In one embodiment of the invention, the side tubes are substantially straight and their number preferably does not exceed four.

In another embodiment of the invention, at least a portion of the side tube is arranged along a frustoconical surface coaxial with the Laval tube, surrounding the Laval tube and converging towards the outlet of the Laval tube. These helical tubes have a regular helical shape, and these helical tubes are arranged at the outlet of the Laval tube, for example, downstream of the approximately straight side tubes if they have outlet holes, or in the immediate vicinity of the outlet. It is open to the outside.

According to the invention, said side tube has a circular cross-section with a diameter not exceeding 4 mm.

In yet another embodiment of the invention, said side tube is annular and surrounds the outlet hole of the central tube.

The nozzle according to the invention is also advantageously divided into at least two parts.

In the present invention, the diameter of the Laval neck is
The thickness is preferably 0.5 mm to 1 mm.

In the structure, the opening angle of the Laval tube is 8° to 12°,
If possible, approximately 10° is desirable.

In another embodiment of the invention, the Laval canal is extended by an element disposed coaxially therewith substantially at its outlet, which element is not widened in the same direction as the diverging portion of the Laval canal. It has a frusto-conical inner surface, the taper of which is greater than that of a Laval tube. of this truncated cone,
The small base forming its own opening is
It is slightly away from the exit end face of the Laval tube, and its diameter is approximately equal to the diameter of the Laval tube exit hole.
It is small enough to make the exit hole of the side tube surrounding the Laval tube invisible in the shank.

To use this nozzle, for example, compressed air is supplied through the inlet of the Laval tube and water is supplied through the side tube. Under these conditions and appropriate pressure, a very uniform mist was observed to emerge from the Laval tube along the opening of the diverging cone leading into the Laval tube.

If the outer surface of the side pipe is combined with a tapered truncated conical surface that serves as a casing, this truncated conical surface is used to form a medium slender member, so that their small diameter portions are adjacent to each other. Advantageously, it is formed by an annular body with an inner surface in the form of two truncated conical surfaces. In this case, the diameter of the small diameter portion and the diameter of the Laval tube outlet differ by less than 1 mm, and the unwidened surface forms the aforementioned extension.

The inventor has determined that such a nozzle, during its use, emits a high level of sound with a relatively narrow frequency band.

The nozzle according to the invention is therefore fitted with a resonator (of the Bermholtz type) at the outlet, which is designed to resonate within the sound range it emits, thereby significantly reducing the level of the sound emitted by the nozzle. It is desirable to

According to an advantageous embodiment of the invention, the resonator device can be formed by a substantially toroidal body which contains a radial crack opening at the outlet of the injector. When only one resonator is provided for a plurality of injectors, a cavity resonator is used that surrounds the entire exit hole of the nozzle and opens there.

The invention also covers the use of the nozzle device described above.

This method mainly involves supplying water to the nozzle at a pressure of up to 6 Kg/ ^cm2 , preferably 0.5 Kg/cm2 below the water supply pressure.
It is characterized by supplying air from ^{the central tube at a pressure of at least 3 kg/cm 2 but} high.

As an example, the diameter of the Laval canal neck is 1 mm;
In addition, the nozzle has four diagonal holes with a diameter of 3 mm, and these holes open into the divergent part of the Laval tube.
Water is supplied at a pressure of 3Kg/cm ² and air is supplied at a pressure of 3.5Kg/cm ² . In this case, the water flow rate is 7 per minute and the air flow rate is 3 Nm ³ per hour.

Under these pressures, the surface temperature is 1000℃ or more.
When cooling objects at 1500℃, the nozzle's cooling capacity is greater than 2Mw/m ² and an extremely uniform cooling effect can be obtained.

An unexpected advantage of this nozzle is that the above-mentioned uniformity is maintained even with large changes in water supply pressure. In fact, even with low water pressure, a mist consisting of fine and well-dispersed water droplets can be obtained.
It was observed that this mist uniformly filled the entire conical jet. On the other hand, if the water supply pressure is increased,
Although the size of the water droplets increases and so does the velocity, they are still distributed evenly in the jet air which is uniformly distributed within the cone-shaped jet. In this way, a nozzle is obtained which maintains uniformity of cooling action even when the cooling power is varied over a wide range (for example in the range 1 to 10).

In the present invention, water and air are supplied to the nozzle in amounts such that the weight ratio of water to air is between 20 and 200.

As already mentioned, these nozzles exhibit a particularly strong cooling power when fog is generated as a result of the injection of water by air. It goes without saying that the air and/or gas supply pressure to the nozzles can be varied in order to vary the composition and texture of this mist. If you change the supply pressure in this way, the cooling power of the nozzle will change accordingly, but when the sound level emitted from the operating nozzle is 80 to 120 db,
The surprising fact has been confirmed that these nozzles reach the most advantageous zone in terms of their cooling capacity.

Therefore, when using the nozzle according to the invention, the level of sound emitted from the nozzle should be
It is advantageous to adjust the air and water supply pressure to 120db.

In addition, as prior art prior to the present invention, Japanese Patent Application Laid-open No. 49-30908 and Japanese Patent Publication No. 48-23657 can be mentioned, and from the latter reference, the angle of inclination of the branch pipe is as follows: A nozzle device is described in which the nozzle device is deviated by 35° to 45° from The device is dedicated to cooling large, high-temperature objects with a surface temperature of 1000°C or 1500°C, and the central tube is supplied with an air-permeable gaseous medium, and the side tubes are supplied with an air-permeable gaseous medium. However, the first cited one supplies oil to a straight central pipe, not a Laval pipe, and compressed air to side pipes. , it is just something that lubricates the needle of a sewing machine, and its structure and industrial uses are not something that should be discussed at the same time.
Even if the inclination angle of the side pipe is somewhat similar to that of the present invention according to the second reference, there is nothing that a person skilled in the art can easily infer from the present invention by combining both of them. , it is certain that this is completely impossible.

Although FIGS. 1 and 2 are examples and illustrations to facilitate an understanding of various aspects of the nozzle according to the invention, the scope of the invention is not limited to these examples.

FIG. 1 shows an axial cross-sectional view of a nozzle whose central tube has a medium narrow shape such as a Laval tube, and near the unwidened end of said central tube with respect to the longitudinal axis of the central tube in the direction of fluid flow. A plurality of slanted side tubes are open.

FIG. 2 shows a cross-sectional view of a nozzle similar to the nozzle of FIG. 1, but additionally provided with a helical side tube, and a cross-sectional view of an annulus placed in front of the nozzle.

In FIG. 1, the air inlet hole is denoted by 1, the water inlet hole is denoted by 2, and the outlet hole for mist consisting of air and water is denoted by 3. The nozzle has two coaxial cylindrical shoulders. The first shoulder 4 has a groove 5 for receiving a packing, and the second shoulder 6 has a thread 7.

Here, we will discuss a method for effectively supplying water and air to a nozzle using two hollow bodies combined in a nested manner.The outer hollow body for water supply is
It is a U-shaped object closed by welded plates. The welding plate has several holes cut with internal threads of the same pitch as the threaded part 7 of the nozzle. The inner hollow body for supplying air has the same U-shape as the outer hollow body and is closed by a welding plate with the same number of holes as the welding plate of the outer hollow body. The holes in the welding plate of the inner hollow body are coaxial with the holes in the welding plate of the outer hollow body, and their diameter is such that they can receive the shoulder 4 of the nozzle easily but in a sealed manner.
The two hollow bodies are partially integrated by an intermediate member and a welded spacer. These hollow bodies are supplied with air and water through suitable tubes attached to the rear. Air supply to the nozzle therefore takes place directly from the inner hollow body, and water supply to the nozzle takes place through the space provided between the outer hollow body and the inner hollow body. The water inlet hole 2 of the nozzle opens into the free space between the welding plates when the nozzle is screwed into the hollow body.

In FIG. 2, a generally cylindrical nozzle body 8 with an axis 9 has a tube section 10 in the form of a Laval tube that is slightly flared along its axis. The unwidened portion of this Laval tube terminates at surface 11. Additionally, two groups of side tubes extend toward the exit of the Laval tube. The first group of lateral tubes consists of four straight tubes opening into the Laval canal at the distal end 13 of the Laval canal divergence, and these straight tubes are arranged regularly around the Laval canal. It is located. The second group of side tubes has an opening 1 on the outer surface around the Laval tube outlet hole.
It is composed of four tapered helical tubes 14 arranged in three directions. The outer surface of these spiral tubes 14 is
It is formed by one ring 16, the inner wall of which has two rings arranged opposite to each other.
It is limited by two frustoconical surfaces 17 and 18. Tapered surface 17 forms the outer surface of helical tube 14, while surface 18 is divergent.
The diameter of the neck 19 is slightly larger than the diameter of the Laval tube outlet and slightly smaller than the minimum diameter corresponding to the outlet hole of the helical tube 14 in the face 15.

The scope of application of the nozzle device according to the invention is very wide, in particular, as mentioned above, for cooling hot liquids, such as liquid slag, for granulation;
cooling of rolling rolls during rolling to extend their service life; cooling of rolled products to give them a defined and homogeneous structure; cooling of continuous casting ingots to increase the withdrawal speed; This includes cooling the oxidized surface to facilitate removal.

[Brief explanation of the drawing]

FIG. 1 is a vertical cross-sectional view of a nozzle that is the device of the present invention;
FIG. 2 is a longitudinal sectional view of the modified embodiment. In these figures, 1... air inlet hole, 2...
...Water inlet hole, 3...Outlet hole, 7...Threaded part, 9...
...Shaft, 14...Spiral tube, 19...Part.

Claims (1)

[Claims] 1 A central canal whose longitudinal cross-sectional shape is the same as that of a Laval canal and a neck diameter of 0.7 mm to 2 mm, and a central canal that opens into the central canal at the divergent end of this central canal or at least one side pipe opening at the outlet of the main pipe, the main pipe being configured to supply a gaseous medium that allows compressed air, and the side pipe being configured to supply water;
and the axis of entry of the side pipe into the central pipe is inclined with respect to the longitudinal axis of the central pipe in the fluid flow direction;
A nozzle device for cooling high-temperature materials, characterized in that the angle of inclination is in the range of 30° to 45°.