DE2750718A1 - SPRAY DEVICE AND PROCEDURE FOR ITS OPERATION - Google Patents

Description

CENTER DE RECHERCHES METALLURGIQUES CENTRUM VOOR RESEARCH IN DE METALLURGIE Association sans but lucratif
Vereniging zonder winstoogmerk
47, rue Montoyer, Brussels / BELGIUM

Spray device and procedure for its mode of operation

The invention relates to a spray device with which a complex substance of gaseous or liquid Quality is to be given a high speed; for example, it should be used for cooling a given surface to be sprayed. Furthermore, the present invention has a method for Operation of this spray device to the subject.

In the field mentioned there is a very large number of spray devices or nozzles that are more or less suitable for the intended use. Of these, there are to be mentioned in particular those which consist of a converging-diverging central tube in the manner of a Laval's nozzle.

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A plurality of lateral tubes inclined to the longitudinal axis open into the diverging part of this central tube a. This type of nozzle can be used on a liquid surface with a very high temperature, for example liquid slag, achieve a high cooling effect: the slag can then be used in a more satisfactory manner Way to be granulated.

The present invention also relates to a type of nozzle which, although primarily used for cooling a high-temperature surface is intended, but under completely different conditions from what the operational Conditions and the nature of the object on which the cooling medium is sprayed applies. This object can be a roller, the temperature of which is uniform, adjustable and controlled in a targeted manner must be in order to achieve a high level without the risk of cracking or changes in their hardness VJaIzen service life to be guaranteed. The object can also be a rolled product that is produced at high temperatures from the Rolling mill exits. The cooling of this product must be controlled in terms of both strength and evenness run so that the product can be given a predetermined and homogeneous structure. After all, it can also be the hot strand in a continuous casting plant, its intensive cooling without the risk of tearing the strand skin allows a noticeable increase in the pull-out speed.

In addition, it is known well that a standing with an oxidizing environment or atmosphere (e.g., air) in contact with high-temperature Oberf1äche quickly forms an oxide layer (scale layer), which is generally for the subsequent machining operations disadvantageous. By spraying a jet of coolant onto this surface using a suitable nozzle

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a thermal shock effect is created, under the influence of which the oxide layer crumbles, so that makes the layer easier to remove. This application also falls within the scope of the present invention.

With such a spray device, the formation of a mist is possible, for example from in air floating fine droplets and at high speed against the wall or surface of the object to be cooled is thrown.

The spray device according to the invention offers the advantage of a particularly high cooling capacity, and this due to their small dimensions (their largest dimension is generally less than 20 mm). In addition, you can use the cooling options in an astonishingly wide range can be varied while ensuring excellent evenness.

Compared to the cooling capacity of the nozzles previously used for the same cooling inserts, the cooled surface of the respective products having a temperature in the range between 1000 ⁰ C and 1500 ° C, that of the spray devices according to the invention is at least twice as large, the devices according to the invention still having the Have the advantage of a particularly uniform operation.

This is because the spray device according to the invention is characterized through a central tube, the longitudinal profile of which corresponds to that of a Laval's nozzle, the neck diameter between 0.7 mm and 2 mm, and through at least one side tube which is near the end of the diverging section or at the exit of the central tube opens into this, the axis of incidence of this lateral line (s) at confluence with the central tube

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is inclined to the longitudinal axis of the latter in the direction of the media outflow and the inclination is preferably over 50 ⁰ and expediently 45 °.

According to one embodiment of the invention, the lateral Tubes essentially straight and should preferably not be more than 4 in number.

According to a further modification of the invention is at least part of the side tubes formed in a spiral shape, The spirals are evenly distributed over a truncated conical surface * which are coaxial with a Laval "see nozzle" is arranged surrounding this and converges towards the output end of the same, and wherein the spirally arranged tubes open into the outlet of this nozzle, for example in the direction of flow behind the possible outlet openings in the essentially straight pipes or outside in the immediate vicinity of this exit.

According to the invention, these lateral tubes have a circular cross section, the diameter of which is not greater is than 4mm.

According to a further embodiment of the invention, the side tube is annular and around the outlet or the The exit opening of the central tube is designed to run around it.

According to the invention, there is also the spray device of at least two elements.

The neck diameter of the Laval's nozzle is preferably between 0.5 mm and 1 mm.

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In terms of construction, the Laval nozzle has a small one Opening of 8 to 12 and preferably of the order of 10.

According to a further modification of the invention, the nozzle is coaxially extended by an element that practically on its exit is arranged and a truncated conical Has inner wall diverging in the same direction as the diverging portion of the nozzle, however, it has a larger conicity than the nozzle, the small base of this area being the actual opening at a small distance from the end face of the nozzle outlet, with a diameter which Diameter of the nozzle outlet opening largely corresponds, but is still small enough that the outlet openings of the side tubes surrounding the nozzle are not axially visible.

This spray device is used in such a way that you have compressed air and, for example, at the nozzle inlet Water is supplied through the side pipes. It was found that under these conditions as well Under the appropriate pressure, a very even mist emerged from the nozzle, spreading over the entire opening of the diverging cone behind the Laval's nozzle distributed.

In cases where the outer surface of the lateral tubes merges with the frustoconical converging surface that serves as a jacket, the latter is expediently produced by means of a circular ring, the inner surface of which has two frustoconical surfaces that form a converging / diverging section and are connected to one another via their small base, which has the same diameter as the nozzle outlet, ie of about 1 mm, the diverging surface delimiting the aforementioned element.

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The applicant found that the noise of such a spray device in use has a high level within a relatively narrow frequency range.

Accordingly, the spray devices according to the invention are expediently provided with an outlet at their outlet Resonator (Helmholz) is provided, which is designed so that it is within the bandwidth of the injector generated noise will resonate, thereby increasing the level of the injector emitted Can noticeably reduce the noise.

According to one embodiment of the present invention, the resonator can be largely toric and with a radial be formed inside circumferential slot with mouth on the exit of the spray device. In such cases where a single resonator is planned for a plurality of spray devices, the resonance cavity is formed by that he has the entire exit openings of the concerned Includes spray devices and opens onto them.

The invention also relates to a method of operation the device described above.

The method according to the invention is essentially characterized in that the injection device is fed

takes place with water under a pressure of up to 6 kg / cm and with air under a pressure which is preferably not should be more healing than 0.3 kg / cm above the water supply

pressure, however, must be at least 3 kg / cm, whereby the air is supplied via the central pipe.

A spray device in which the neck diameter of the nozzle is 1 mm and which has four inclined and in the diverging zone of the Laval 'see nozzle opening out openings of 3 mm diameter is provided

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for example with water under a pressure of 3 kg / cm and air is introduced under a pressure of 3.5 kg / cm, the corresponding throughput rates being 7 l / min Water and 3 Nm / h for air.

At these pressures, the cooling performance of these spray devices for products whose cooled surface performs a temperature of 100O ⁰ C to 150o C ^0, larger than 2 MW / m of the cooling effect at the same time particularly remarkable regularity.

An advantage that could not have been foreseen with this spray device is that this uniformity in the water supply even with strong pressure fluctuations. It was found that at low water pressure the one produced consisting of well-dispersed water particles with a very small diameter Mist evenly filled the entire spray cone. It has also been shown that the water supply pressure increased the water particles act as larger and with a higher speed, but at the same time also as well dispersed in the atomizing air and evenly distributed in the spray cone. The practical The result is that according to the invention a spray device is created which over a wide area Range of fluctuations in their cooling capacity (on the order of 1:10) have the advantage of even cooling does not lose.

According to the spray device are water and Air supplied in such amounts as these correspond to the weight ratio of water to air in the range 20 to 200.

As already stated elsewhere, the above-described spray devices offer a particularly intensive one or high cooling capacity, because the atomization of the

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V / assers created a mist by air. It is obvious that the pressures in the supply of the injection * devices with air or gas can vary to the composition and structure of the aforementioned To change the fog. These changes correspond to a changed cooling capacity or cooling power of these spray devices, however, it was found, completely surprisingly, that from the standpoint of cooling performance this Spraying devices arguably the most interesting zone was reached when the level of the in operation The sound emitted by the spray device was between 80 and 120 dB.

Thus, according to the invention, it is when a spray device is used of the type described above is advantageous, the pressures of the air or the water for charging them To regulate the device so that the level of sound or noise emitted by this device between 80 and 120 db.

The enclosed Figures 1 and 2, which are to be considered only as an example and in a non-restrictive sense are, the various structural modifications of a spray device according to the invention should be understandable do:

1 is an axial section through a spray device, the central tube of which is designed in a converging-diverging manner, in the manner of a Laval's nozzle, against the diverging end of the same has a plurality of to the central pipe axis in the direction of the media outflow side open inclined side pipes.

Fig. 2 shows a longitudinal view of a spray device, which is similar to that of FIG. 1 and also with lateral spiral tubes is provided, as well as a section through a ring arranged in front of the spray device.

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According to FIG. 1, a distinction is made between an air inlet opening 1, water inlet opening 2 and an air / water mist outlet opening Z> · The spray device has two cylindrical, coaxial shoulders, the first shoulder 4 having a groove for receiving a seal and the second shoulder 6 is provided with a threaded portion 7.

At this point the reference to a very satisfactorily working system for supplying the injection device with water and air via two boxes nested one inside the other seems appropriate. The outer box for the water supply has the shape of a U, which is closed by a welded flat iron. A certain number of threaded holes with the same thread as the threaded section 7 of the spray device are formed in the flat iron. The inner box for the air supply has the same U-shape, whereby the flat iron that is welded on at the end has the same number of holes as the flat iron of the outer box. The holes in the inner box are coaxial with the holes in the flat bar of the outer box; the diameter of the openings is chosen so that the shoulder K of the spray device can be easily but tightly inserted into it. The two boxes are fixed in relation to one another in terms of position by means of intermediate pieces and cross braces in a welded design. The two boxes are supplied with air and water via appropriate lines attached to the rear of the same. Thus, the supply of air to the spray devices is effected directly from the inner box and with water via the spaces between the outer and inner boxes. The water inlet openings 2 of the spray devices open into the free space between the welded flat iron after the spray devices have been screwed into the boxes.

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Like from Pig. 2, the actual spray device 8 has an essentially cylindrical shape its axis 9 see a drill 10 in the manner of a Laval's Nozzle with a slight divergence. The diverging section of this nozzle ends with the surface 11. On the There are arrangements of side tubes, the first of which consists of four straight tubes 12 opening into the nozzle at the end of the diverging section of the same at 13 and evenly distributed around this nozzle, and the second consisting of four spiral tubes 14 in converging design and at 15 in the outer surface of the nozzle opening out, which are arranged around the outlet opening derseloen. The outer surface of these tubes 14 forms a circular ring 16, the inner wall of which by two mutually facing frustoconical surfaces 17 and 18 is formed, wherein the converging surface 17 represents the actual outer surface of the tubes 14, while the surface 1 & diverging formed ü. Of the The neck diameter 19 is somewhat larger than the diameter of the nozzle outlet and somewhat smaller than the minimum diameter corresponding to the outlet openings of the tubes 14 to area 15.

The range of application for the spray device according to the invention is very wide and extends, as already at performed elsewhere, especially on cooling the surface of a high temperature liquid, for example, of liquid slag with regard to slag granulation, a roller in a rolling mill during their use to ensure a long service life of the same, a rolled product, so this one given a predetermined and even structure

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a hot strand in a continuous casting plant in order to increase the strand pull-out speed, as well as a oxidized surface for easier descaling.

PATENTED KITCHEN

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Claims (13)

PATENT CLAIMS: 1.JSpritzvorrichtung, characterized in that a ^ - central tube, the longitudinal profile of which corresponds to that of a Laval's see nozzle (1,3,10), a neck diameter between 0.7 and 2 mm and at least one lateral tube (2,12), which near the end (3, 11) of the diverging section or at the exit of the central pipe opens into this, the incidence axis of this lateral line (s) in the form of the pipe being inclined when it joins the central pipe to the longitudinal axis of the latter in the direction of the media outflow and the Inclination is preferably over 30 ° and expediently 45 °. 2. Apparatus according to claim 1, characterized in that the lateral tubes (12) are provided in a substantially straight manner and no greater than 4 in number. 3. Device according to claims 1 and 2, characterized in that the lateral tubes have a circular cross-section, the diameter of which is not greater than 4 mm. 4. Device according to claims 1 and 2, characterized in that at least some of the lateral tubes (14) are formed spirally, the spirals are evenly distributed over a frustoconical surface which is arranged coaxially with the Laval's: hen nozzle (10) surrounds it and converges towards its exit. 809820/0969 ORIGINAL INSPECTED 5. Apparatus according to claim 1, characterized in that the lateral tube is annular (16). 6. Device according to claims 1 to 5, characterized in that it consists of at least two elements. 7. Device according to claims 1 to 6, characterized in that the neck diameter of the Laval's see nozzle according to the invention is preferably between 0.5 mm and 1 mm. 8. Device according to claims 1 to 7, characterized in that the opening of the Laval's see nozzle between 8 ° and 12 °, preferably 10 °. 9. Device according to claims 1 to 8, characterized in that the nozzle (10) is coaxially extended by an element which is practically located at its outlet and has a truncated conical inner wall (18) which diverges in the same direction as the one The nozzle section diverges, but has a larger conicity than the nozzle, the small base of this surface forming the opening at a short distance from the end surface (11) of the nozzle outlet with a diameter which is the same or almost the same as the diameter of the nozzle outlet opening and is small enough to cover the exit openings of the side tubes surrounding the nozzle in the axial direction. 10. Device according to claims 1 to 9, characterized in that the Spritζvorrichtungen are provided individually or together at their output with a Helmholtz resonator which is dimensioned so that it is within 809820/0969 the bandwidth of that produced by the spray device j The sound resonates. 11. A method for operating the spray device according to claims 1 to 10, characterized in that the charging of the device is carried out with water under a pressure of up to 6 kg / cm ² and with air under a pressure which should preferably not be higher than 0.5 kg / cm ² above the water supply pressure, but at least 3 kg / cm ² , with the air supply taking place via the central pipe. 12. The method according to claim 11, characterized in that the spray device water and air are supplied in quantities whose weight ratio of water to air is between 20 and 200. 13. The method according to claims 11 and 12, characterized in that the pressures of air and water for charging the spray device are set to a sound level of the sound emitted by the device between 80 and 120 db. 809820/0969