EP2190587B1 - Multi-hole or cluster nozzle - Google Patents

Abstract

A multi-hole or cluster nozzle having several outlet openings for fluid to be atomized. The central longitudinal axes of at least two of the outlet openings are aligned askew relative to one another, where a distance between the central longitudinal axes of these outlet openings and the main longitudinal axis of the nozzle is initially reduced when seen in the outflow direction, without intersecting the central longitudinal axis, and increases again after passing through a minimum distance. Use for example in nozzles for evaporative cooling or for flue gas cleaning.

Description

The invention relates to a multi-hole or bundle nozzle with a plurality of outlet openings for fluid to be atomized.

Multi-hole nozzles are nozzles in which the droplet spray, starting from a common pre-chamber or mixing chamber, exits via a plurality of individual bores.

Bundle nozzles are nozzles in which several basically functional individual nozzles are mounted on a nozzle head or within a nozzle head.

Multi-hole nozzles and bundle nozzles have in common that several spray jets simultaneously emerge from the nozzle and form a total exit jet. Within the total exit jet can, but does not necessarily have to be an interaction or mixing of the individual beams. The invention thus relates to nozzles for atomizing liquids without and with the use of compressed air, wherein alternatively a plurality of individual nozzles are mounted on a nozzle lance head, or flows out of a common chamber liquid or a drop-gas mixture of a plurality of outlet openings in the nozzle outlet part. With the invention novel measures for producing a fine droplet spray while avoiding deposits on the nozzle exit part are to be used in such multi-hole or bundle nozzles.

In many process plants, liquids are sprayed into a gaseous fluid, for example in flue gas to be cleaned or cooled, ie for flue gas cleaning or for evaporative cooling. It is often crucial that the liquid is atomized into the finest possible drops. The finer the drops, the larger the specific drop surface. This can result in considerable procedural advantages. For example, the size of a reaction vessel and its manufacturing costs are critically dependent on the average droplet size. But in many cases it is by no means sufficient for the average droplet size to fall below a certain limit. Even a few much larger drops can lead to significant disruption. This is particularly the case when the drops do not evaporate fast enough due to their size, so that even drops or doughy particles in the following components, eg fabric filter hoses or fan blades, are deposited and lead to malfunction due to incrustations, corrosion or imbalance ,

When liquids are to be atomized to a very fine droplet spray, so-called pressurized gas-based two-fluid nozzles are frequently used in addition to high-pressure single-fluid nozzles, which are charged only with the liquid to be atomized. In these nozzles, the liquid is removed by means of a pressurized gas, e.g. Compressed air or pressurized steam, the first gaseous fluid, into a second gaseous fluid, e.g. in flue gas, sprayed.

definitions:

In the interests of a linguistic simplification, the term "compressed air" is often used in the following for the designation of the first gaseous fluid, the term "compressed air" including the use of pressurized gas or pressurized steam having essentially any desired chemical composition. Furthermore, as a rule, the second gaseous fluid is referred to as a flue gas, the use of the term "flue gas" including any other gaseous and possibly additionally solids-laden fluid.

The description of the invention focuses on the more complicated case of the compressed-air two-fluid nozzle. However, the invention is also applicable to single-ink atomizing nozzles, provided that they are designed as a multi-hole or bundle nozzles.

Operational problems with nozzles and weaknesses of laboratory tests:

In conjunction with the energy expenditure required for atomization, the characteristics of the droplet spray produced are of crucial importance. In this context, the following problem has to be pointed out: The metrological detection of the droplet size distribution in the spray, which is generated with a nozzle, is generally carried out under idealized boundary conditions in fluid flow laboratories. In the process, the boundary conditions occurring in large-scale plants are in some cases considerably falsified. Thus, for example, the dust content of the flue gas or the loading of the flue gas with easily condensable gases in the laboratory is not replicated. And for this reason, the results obtained in the laboratory are only partially to be transferred to the long-term operation of large-scale plants. As readily condensable gaseous constituents of flue gas in particular sulfur trioxide or sulfuric acid may be mentioned. But even in the absence of sulfuric acid, even undershooting the water vapor sump can lead to considerable problems due to deposit formation. For example, while the sulfuric acid dew point temperature may range between 100 ° C and 160 ° C, the steam dew point temperatures in flue gases are often between about 45 ° C and 65 ° C. Since a comparatively cold fluid is usually sprayed into the flue gas with two-substance nozzles, the surface temperature of the nozzle lance and nozzle head, in particular those of bundle nozzle heads, is well below the dew point temperatures of the flue gas constituents mentioned. From the flue gas to nozzle lance and nozzle head condensing liquid can chemically react with the particulate contents of the flue gas, the airborne dusts. So it is easy to see that dust particles with a high calcareous content (CaO) react with the sulfuric acid (H ₂ SO ₄ ) condensing sulfur trioxide content of the flue gas to gypsum (CaSO ₄ ), so that hard and firmly adhering deposits can build up. But falls below the Wasserdampftaupunkts at the lance or nozzle surface does not even require a sulfuric acid content of the flue gas. Even a low sulfur dioxide content is sufficient for the construction of hard coatings, as far as the fly ash, eg CaO or MgO. And a deposit formation is already possible, if only water vapor condenses and the condensate sets with deposited airborne dusts.

However, if deposits grow up in the area of the nozzle outlet openings, it is almost unavoidable that droplets from the spray are deposited on these surfaces and that liquid films form here, as discussed Fig. 1 will be explained in more detail. Relatively large secondary droplets detach from these liquid films in the region of low shear stress forces. While with a modern two-fluid nozzle, in principle, maximum droplet sizes of, for example, 20 to 100 μm can be achieved, the droplets which detach from the liquid films may well have diameters of 500 to 3000 μm. For such large drops, the residence time is far too short even in large-scale plants, as that even only approximately complete evaporation could succeed. Impermissibly high moisture contents of the product occurring in subsequent components of the system can be the result. It is treacherous here that the deposits on the nozzle heads usually have developed so far only after some time that they exert a strong disturbing influence on the droplet size distribution. While very good results are achieved in a nozzle equipped with nozzles, it can be used with the Time to a significant impairment of the operation come when the pads have increased accordingly.

Thus, there is a great interest in avoiding as much as possible deposits on nozzle lances in the vicinity of the nozzles and on the nozzles themselves.

For nozzles with a single outlet bore deposits can be avoided in a known manner by means of a fogging or Hüllluft device, see for example the international patent publication WO 2007/098865 ( PCT / EP 2007/001384 ). In this case, air with a comparatively low pre-pressure, for example, about 40 mbar, passed through a the actual nozzle lance enclosing cladding tube to the nozzle head, and placed at a comparatively low speed as against the flue gas shielding Hüllluft- or Schleierluft-jacket to the emerging from the nozzle drop stream , Thus, a formation of deposits on the single-nozzle bore should be largely ruled out here. And even at the nozzle lances, the formation of deposits is largely suppressed. The latter is due to the fact that the Schleierluftschicht in the outer tube is a thermal insulation against the cold nozzle lance, so that the outer skin of the Hüllluft tube assumes approximately the flue gas temperature, which is a quenching flue gas ingredients prevented in most cases.

In conventional nozzles with multiple outlet holes or in bundle nozzles, the supply of the nozzle head area with fog air causes great difficulties, as will be explained below. In such nozzles according to the prior art, the distance between the individual passage openings is very large, such as in Fig. 1 and Fig. 2 can be seen. Each individual nozzle acts like a jet pump: it sucks in gaseous fluid, eg flue gas, from the environment and mixes it into the spray jet. This gaseous fluid thus flows partially over the cold front surface of the nozzle to the passage opening and, consequently, it may come to the growth of deposits here, at least when it is the gaseous fluid is flue gas. But even then, if no flue gas reaches the cold front surface of the nozzle, it can come here over time to deposit formation. In this case, the coverings from the contents of the liquid to be atomized itself arise. This is usually not from solids-free liquid, eg from demineralized and ultrafine filtered water, but from additional process water, which is loaded with dissolved substances. As in Fig. 1 is shown, recirculation vortices 17 can be generated by the jet, which return small drops on the front surface of the nozzle. If the liquid finds the opportunity to evaporate here, even if only partially, the ingredients inevitably grow as deposits.

For a multi-orifice nozzle, this is for example in Fig. 1 where also the liquid film 12 on the coating as well as resulting large secondary drops 13 are shown. Critical in such nozzles with multiple outlet holes, in particular the central region, which often carries no design hole due to the design. A first step to improve the boundary conditions would be a redesign of the construction of a multi-hole nozzle in such a way that a central outlet bore is possible. By arranging a curtain air nozzle according to the prior art, the formation of deposits from flue gas constituents can be prevented in such nozzles with a plurality of outlet bores. However, a relatively large enveloping air volume flow is required if lining formation on the front face of the nozzle is to be prevented reliably. Of course you do not want to add a lot of cladding air to the nozzle jet, because it is not supposed to be cooled by cladding air, but by the evaporation of the flue gas. Thus, there is a strong interest in keeping the front face of the nozzle, which is suitable for a deposit formation, as small as possible or to reduce the distance between the individual nozzle exit bores as far as possible. For nozzles after the In the prior art, this is not possible because for this purpose the exit holes would have to be arranged close to the central axis, such as Fig. 1 can be seen. But then the inflow to these nozzle holes is very unfavorable and associated with high pressure losses and flow separation in the outlet holes and an unsatisfactory atomization.

Even more critical is the situation with bundle nozzles of the prior art, as in Fig. 2 is shown. This would have to work with a lot of air and with a visually complex veiling air nozzle head, if a deposit formation from flue gas ingredients should be reliably prevented. A deposit formation from the solids content of the liquid to be atomized is hereby not yet to avoid.

With the invention, a multi-hole or bundle nozzle is to be provided in which a deposit formation is at least greatly reduced and which enables the generation of a total spray jet with a large spray angle.

According to the invention, a multi-hole or bundle nozzle according to claim 1 is provided for this purpose.

The invention thus achieves a convergent / divergent arrangement of the exit jets, so that, on the one hand, the exit bores of nozzles having a plurality of outlet openings or of bundle nozzles can be grouped as closely as possible about the axis of the nozzle head and on the other hand, the possibility of forming a total spray jet having a sufficiently large spray angle is provided. In addition, the nozzle configuration according to the invention has only a small amount of fog required. The minimum distance of the central longitudinal axes of the outlet openings of the individual nozzles lies in the mouth region of the entire nozzle, so it can still be arranged in the mouthpiece upstream of the outlet openings, at the level of the outlet openings or downstream of the outlet openings. In this case, a region of the minimum distance lying immediately downstream of the outlet openings is preferred in order to be able to realize an expansion of the overall jet shortly after the nozzle.

As a result of the convergent / divergent arrangement of the individual exit jets, the exit jets emerging from the individual nozzle holes or from the individual individual nozzles thus form a flow focus in the mouth region of the entire nozzle, wherein this flow focus may also lie within the mouthpiece. The term "flow focus" is not to be seen in the narrow sense, but in terms of a minimum cross-section of the total jet, upstream and downstream of this minimum cross-section is a larger cross section of the total beam.

The basic idea of the invention is thus to align the individual nozzle jets or exit jets in such a way that the beam forms, as it were, a flow focus at the point of entry into a process space in which it is sprayed. The individual nozzle jets or exit jets are already inclined towards the main axis or center longitudinal axis of the nozzle before reaching the flow focus or the minimum cross section, but are not strictly aligned with this center longitudinal axis, but aim at the center longitudinal axis in the center. In this case, the center of the total beam may be formed by the exit jet of a central nozzle, which is aligned parallel to the central longitudinal axis.

In a further development of the invention, the at least two outlet openings are arranged annularly around the central longitudinal axis of the nozzle.

In this way, a compact arrangement of the outlet openings is achieved and, for example, an annular arrangement of the outlet openings, a rotationally symmetrical total spray can be generated. For adapting the shape of the total spray jet to given geometrical conditions, it is also possible, for example, to realize ring configurations in elliptical or triangular form.

In a further development of the invention, the central longitudinal axes of the at least two outlet openings, as seen on a plane containing the main longitudinal axis of the nozzle, are arranged at the same angle to the main longitudinal axis on the nozzle.

In a further development of the invention, the central longitudinal axes of the at least two outlet openings are inclined in the same direction with respect to a circumferential direction about the main longitudinal axis of the nozzle.

In this way, the entire spray jet can be imparted a twist.

In a further development of the invention, the central longitudinal axes of the at least two outlet openings lie on the lateral surface of an imaginary hyperboloid of revolution.

By these measures, a rotationally symmetrical total spray can be generated, which is impressed a twist around the central longitudinal axis of the nozzle.

In a further development of the invention, the jet streams generated by means of the at least two outlet openings can be largely without Spread interaction with each other in a process space downstream of the outlet openings.

In this way it can be achieved that the droplet sizes in the total spray jet of collision processes between individual drops are substantially independent and are determined exclusively by the atomization properties of the individual nozzles or of the individual outlet openings.

In a further development of the invention, a central outlet opening lying on the main longitudinal axis of the nozzle is provided around which the at least two further outlet openings are arranged in an annular manner.

Advantageously, in such a nozzle with a central outlet opening, the central longitudinal axes of the at least two further outlet openings are inclined in the same direction with respect to a circumferential direction about the main longitudinal axis of the nozzle in order to generate a twist about the main longitudinal axis of the nozzle.

In a further development of the invention, a, the outlet openings surrounding and acted upon with compressed air annular gap nozzle is provided.

The provision of an annular gap nozzle is advantageous in order to avoid liquid films in the region of the nozzle orifice, which can lead to secondary drops of considerable size. The annular gap nozzle can be acted upon with compressed air at high pressure or even to produce enveloping air only with low-pressure veiling air.

In a further development of the invention, the outlet openings are provided in a nozzle mouthpiece which is surrounded by an annular gap nozzle.

In such a design, the outlet openings are provided, for example, as holes in a massive nozzle tip. This Nozzle tip may be surrounded by an annular die to avoid the formation of large secondary drops.

In a further development of the invention, a nozzle carrying body is provided on which a plurality of nozzle nozzles projecting in the outflow direction individual nozzles are arranged, wherein the individual nozzles are surrounded at least at the level of their outlet openings of an annular gap nozzle hood, so that between the individual nozzles and the annular gap nozzle hood at the level of the outlet openings Annular gap is formed.

Advantageously, in such a design of the nozzle can be provided that a central nozzle are provided with a lying on the main longitudinal axis of the nozzle outlet opening and at least two further, the main longitudinal axis of the nozzle annular surrounding individual nozzles, wherein an end face of the annular gap nozzle hood has one or more annular gap openings, so that at the level of the outlet openings, a distance between an outer circumference of the individual nozzles and the annular gap or openings or the outer circumference of adjacent individual nozzles is substantially equal.

In this way, an approximately constant annular gap width of the annular gap nozzle can be achieved by an annular gap opening in the annular gap nozzle hood, for example in the form of a star with rounded points or, if appropriate, also irregularly designed annular gap opening. But an annular gap between the housings of the individual nozzles then has the substantially constant annular gap width, so that approximately the same flow velocity of the annular gap air is achieved substantially over the entire annular gap, which may have a geometrically irregular shape. If cylindrical housings of the individual nozzles contact one another, a constant annular gap width can not or only approximately be achieved. Optionally, a throttle element may be provided upstream of the annular gap in the intermediate space between the individual nozzles or the inside of the annular gap nozzle hood be to reduce the pressure of the annular gap air in a suitable manner.

In a further development of the invention, the annular gap nozzle is surrounded by an annular Schleierluftdüse.

In this way, the annular gap nozzle in the region of the nozzle orifice can be shielded from flue gases in the process space.

In a development of the invention, a nozzle carrier body is provided on which a plurality of nozzle bodies projecting outwardly in the outflow direction are arranged individual nozzles, wherein the individual nozzles are arranged on a discharge face viewed in the generally concave front of the nozzle carrier body.

In this way, the convergent / divergent arrangement of the exit jets of the individual nozzles or the corresponding associated alignment of the individual nozzles can be achieved by the shaping of the nozzle carrier body. As a concave front not only a curved front, but for example, a front surface is considered, which consists of a plurality of flat partial surfaces, which together form a depression.

In a further development of the invention, the outlet openings are provided in a nozzle mouthpiece, wherein the nozzle mouthpiece has a base body with a conical outer surface and surrounding the base body and partially fitting on the outer surface hood and wherein the base body and / or the hood have at the outlet openings ending nozzle channel grooves.

In this way, the nozzle channels in the arrangement according to the invention can be realized in a simple manner by the milling of grooves in the cone-shaped base body and / or the hood. To the grooves are then closed at their open side and form the nozzle channels. The grooves are applied, for example, on the cone-like base body as in the manufacture of a helical bevel gear.

Fig. 1

eine Schnittansicht einer Viellochdüse nach dem Stand der Technik,

Fig. 2

eine stark vereinfachte Seitenansicht einer Bündeldüse nach dem Stand der Technik,

Fig. 3

eine abschnittsweise Schnittansicht einer Bündeldüse gemäß einer ersten Ausführungsform der Erfindung,

Fig. 4

eine Schnittansicht einer Viellochdüse gemäß einer zweiten Ausführungsform der Erfindung und

Fig. 5

eine schematisch Darstellung eines Düsenmundstücks gemäß einer dritten Ausführungsform der Erfindung.

Further features and advantages of the invention will become apparent from the claims and the following description of preferred embodiments of the invention in conjunction with the drawings. Individual features of the illustrated and described embodiments can be combined with one another in an arbitrary manner, without exceeding the scope of the invention. In the drawings show:

Fig. 1

a sectional view of a multi-hole nozzle according to the prior art,

Fig. 2

a greatly simplified side view of a bundle nozzle according to the prior art,

Fig. 3

1 is a sectional view of a bundle nozzle according to a first embodiment of the invention,

Fig. 4

a sectional view of a multi-hole nozzle according to a second embodiment of the invention and

Fig. 5

a schematic representation of a nozzle orifice according to a third embodiment of the invention.

The presentation of the Fig. 1 gives a rough outline of the prior art and shows a multi-hole nozzle 3 with an axis of symmetry 16, consisting of a feed tube 2 for the liquid to be atomized 1, a feed pipe 4 for the compressed gas or for the compressed air 6, an inlet part 20 for liquid. 1 and compressed gas 6 in the mixing chamber 7 with a bore 10 for the liquid supply 1 and a plurality of bores 5 for the compressed air supply 6. In the mixing chamber 7, an anvil 15 is arranged with a baffle 11, is already divided at the entering through the bore 10 liquid in relatively small drops. This primary droplet spray is conveyed by the compressed air to the outlet holes 8. Due to the strong pressure reduction and acceleration downstream of the outlet bores 8, the medium-sized droplets 9 producing in the mixing chamber 7 are broken down into substantially smaller droplets. From the holes 8, the compressed gas-promoted droplets 18 exit. Very fine drops are present in the jet core, while at the edge of the jet comparatively large drops occur which result from the decay of wall-liquid films in the bores 8, in particular at the bore edges. This in any case if no annular clearance air is provided. At the nozzle, a central Feststoffbelag 14 has formed. By Rezirkulationswirbel 17 smaller drops are deposited on the central coating 14 and form a liquid film 12. At the tip of the nose 21 of the solid coating 14 very large secondary drops 13 dissolve out of the liquid film.

The presentation of the Fig. 1 For the sake of simplification, the external configuration of a bundle nozzle 26 according to the prior art is shown. In bundle nozzles according to the prior art, the individual nozzles 36 are mounted on the front surface 38 of an outwardly curved cone, ie in the outflow direction, that is convex. Although this overall spray jets are readily obtainable with a large total opening angle α, but these conventional nozzles have a very large cold front surface 38, which is not readily shielded by the use of fog air and easy on it to the formation of large secondary drops triggering deposit formation can come. In principle, it does not matter whether the individual nozzles consist of single-substance atomizing nozzles or of compressed air-supported two-component nozzles.

Fig. 3 1 shows a plurality of individual nozzles, namely a central nozzle 46 and one of six annular nozzles 47 which are arranged around the central nozzle 46 in such a way that they almost touch the central nozzle 46 in the mouth region 40 , Instead of six annular nozzles 47, any other number of individual nozzles larger than two may be provided. The central longitudinal axes of these arranged as a ring ring nozzles 47 do not intersect with the main longitudinal axis 16 of the central nozzle 46; Rather, the ring nozzles 47 "aim" laterally past the central nozzle 46. The central longitudinal axes of the annular nozzles 47 are thus skewed aligned with each other, with a distance between the central longitudinal axes of the annular nozzles 47 and the central longitudinal axis of the central nozzle 46, which simultaneously represents the main longitudinal axis 16 of the entire nozzle, seen in the outflow initially reduced. However, the central longitudinal axes of the annular nozzles 47 do not intersect the main longitudinal axis 16. Rather, the distance between the central longitudinal axes of the annular nozzles 47 and the central longitudinal axis 16 increases again after passing through a minimum distance or smallest cross section of the total exit jet. This region of minimum distance is a little more than the diameter of the outlet openings of the individual nozzles 46, 47 downstream of these outlet openings. Overall, therefore, so that an initially convergent and after passing through the smallest cross-section again divergent arrangement of the spray jets 18 of the individual nozzles is achieved.

The spray jets 18 emerging from the annular nozzles 47 have, as in Fig. 3 can be seen, all an equal circumferential component with respect to the main longitudinal axis 16, as seen in the circumferential direction about the main longitudinal axis 16 are all inclined in the same direction. The central longitudinal axes of the annular nozzles 47 and the spray jets 18 of these annular nozzles 47 are due to the annular arrangement of the annular nozzles 47 thus on the lateral surface of a Rotationshyperboloids.

The overall jet of the bundle nozzle 45 is affected by the selected orientation of the annular nozzles 47 in total with a twist about the main longitudinal axis 16.

Since the individual spray jets 18 do not penetrate one another, each spray jet 18 can propagate largely freely in the process space downstream of the nozzle 45, so that a total spray jet with a sufficiently large opening angle α is formed.

The bundle nozzle 45 has a central lance tube 2 for the supply of liquid to be sprayed 1 and a lance tube 4, which coaxially surrounds the central lance tube 2, for the supply of compressed air 6. In a nozzle support body 41 with concave front surface on which the annular nozzles 47 and the central nozzle 46 are arranged, bores 27 for the supply of liquid to the individual nozzles 36, 37 are provided. Via finer holes 10 in the mixing chamber inlet parts 28, which are each arranged at the transition between the nozzle support body 41 and the nozzle tubes of the individual nozzles 46, 47, the liquid enters the mixing chambers 7 a. The annular nozzles 47 are identical to the central nozzle 46 is formed. Furthermore, the compressed air 6 initially flows through large bores 31 into a primary compressed gas chamber 32 and reaches the mixing chambers 7 via bores 5 in the nozzle tubes of the central nozzle 46 or the annular nozzles 47.

In the mixing chamber 7 and in the adjoining nozzle channel, the liquid is atomized at sound velocities of the gas phase to such fine droplets that a further constriction at the downstream end of the nozzle tube, which forms the respective outlet opening 8, is usually not required.

The primary compressed gas chamber 32 is formed between the nozzle support body 41, a nozzle hood 23, the nozzle tubes of the central nozzle 46 and the annular nozzles 47 and a throttle disc 35. The throttle disc 35 has a plurality of openings through each of which a single nozzle, so the central nozzle 46 and the annular nozzles 47, projects therethrough, wherein the respective openings are slightly larger than the outer diameter of the respective nozzle tubes, so that an annular gap between the throttle plate 35 and each Nozzle tube is formed.

A secondary compressed gas space 34 downstream of the throttle plate 35 is surrounded by the nozzle hood 23 of the annular gap nozzle so that only relatively narrow gaps 25 between the nozzle tubes 40 of the individual nozzles 46, 47 and the nozzle hood 23 of the annular gap nozzle arise at the nozzle outlet, from which the gap air at high speed exit. The opening of the annular gap cover 23 is irregular and designed so that the resulting annular gap has a substantially constant width.

In the central region of this bundle nozzle 45 no deposits can grow up, since no corresponding surfaces are offered here. Pads could possibly grow on the front side of the nozzle hood 23 of the annular gap nozzle, since this can be cooled slightly below a dew point temperature of the flue gas. Through a Schleierluftdüse 29, which is charged with purging air at a comparatively low pressure, for example 40 mbar, the annular nozzle 23 is shielded from the flue gas. The outer skin of the Schleierluftdüse 29 reaches approximately the flue gas temperature, so that in general is not expected to fall below a dew point and a deposit formation can be largely excluded. The concept presented by means of the bundling nozzle 45, which is designed as a two-substance nozzle, with a flow focus corresponding to a convergent / divergent arrangement of the individual exit jets 18 in the vicinity of the nozzle orifice 40 can of course also be applied to single-component atomizing nozzles.

According to the invention, in the bundle nozzle 45 thus a central nozzle 46 and around this central nozzle 46 around six further annular nozzles 47 are grouped, which lean against the outlet section of the central nozzle 46 and which are inclined in the same direction in the circumferential direction in the form of a twist rose. After passing through the flow focus, ie the minimum cross section of the total exit jet, the bundle nozzle 45, the individual spray jets 18 thus run divergent, so that sufficiently large total jet opening angles α can be generated. With a nozzle configuration of this type, there is hardly any front surface available for the growth of coverings, and thus only a small volume of bleed air through the sander air nozzle 29 is required. Furthermore, such nozzle heads can be made relatively slim.

Of course, a bundle nozzle of this type can be constructed from individual nozzles, which are each equipped with annular gap atomization at the nozzle orifice, as for example in the international patent publication with the file reference PCT / EP 2007/001384 for single nozzles has been described. But with bundle nozzles, of course, it is also possible to supply the annular gap air 25 for the individual nozzles of the nozzle bundle via the contiguous primary compressed air space 32. In order not to lose too much energetic compressed air via the annular gap atomization, a throttle element between the primary compressed air space 32, from which the primary atomizing air for the individual nozzles 46, 47 is removed, and the annular gap 24 supplying secondary compressed air space 34 can be installed. The secondary compressed air space 34 is limited by the throttle disk 35, the nozzle hood 23 and the nozzle tubes 36. By the throttle element in the form of a throttle plate 35 with a number of passage openings corresponding to the number of nozzles 46, 47, thus the space within the annular gap nozzle hood 23 is divided into the primary compressed air space 32 and the secondary compressed air space 34. In the primary compressed air space 32 there is a greater pressure and starting from this primary compressed air space 32, the atomizing air is diverted via the holes 5 in the mixing chambers 7 of the individual nozzles 46, 47. In the secondary compressed air space 34 there is a lower air pressure, which then feeds the annular gap 24 between the annular gap nozzle hood 23 and the respective outer circumference of the nozzle tubes as well as the gap between the nozzle tubes of the individual nozzles 46, 47. In order to further reduce the compressed air consumption for the annular gap supply, the annular gap 24 of the annular gap nozzle can be adapted to the contour of the individual nozzles 46, 47 at a distance of, for example, 0.5 to 1 mm. A relatively simple production technique consists here of first producing the blank of the nozzle hood 23 of the annular-gap nozzle with a closed front surface and placing it on the blank of the nozzle-carrying body 41 of the bundle nozzle. Then, the passage bores for the individual nozzles on the front surface of the nozzle hood 23 of the annular gap nozzle can be introduced with a position of the bore axes which coincide with the position of the central longitudinal axes of the individual nozzles 46, 47 to be installed later. The individual bores are driven through the front surface of the nozzle hood 23 of the annular gap nozzle into the nozzle support body 41, so that a perfect alignment of the central longitudinal axes of the individual nozzles and the axes of the individual annular gap openings is ensured.

The fact that an envelope or Schleierluftdüse 29 may be provided in addition, requires no further explanation for the expert. Here, however, the veiling air 33 would only be required to avoid deposits on the nozzle lance or on the outer edge of the annular gap nozzle, so that it is possible to work with a comparatively small amount of veiling air. Of course, the outer contour of the annular gap nozzle or the inner contour of the Schleierluftdüse could be designed such that annular gaps arise in the form of rounded stars corresponding to the envelope of the individual nozzles.

The presentation of the Fig. 4 shows a multi-hole nozzle 43 according to the invention. As with the bundle nozzle 45, which in Fig. 3 is shown here, the principle is followed that all spray jets 18, which originate from the individual outlet openings, emerge from the central region of the nozzle head. The directivity of the spray jets 18 is also achieved here in that the holes 8, at the downstream end of the outlet openings, within the nozzle head in the view of Fig. 4 approximately diagonal. The central longitudinal axes 44 of the individual bores 8 and thus the outlet openings are skewed to each other, inclined in the same direction with respect to a circumferential direction about the main longitudinal axis 16 of the nozzle and the distance of the central longitudinal axes 44 to the main longitudinal axis 16 of the total nozzle initially decreases, seen in the outflow, without the main longitudinal axis 16 to cut. After passing through a minimum distance between the central longitudinal axes 44 and the main longitudinal axis 16 of the overall nozzle, this distance increases again, so that a convergent / divergent arrangement is formed. The central longitudinal axes 44 of the individual bores 8 are thus due to the annular arrangement of the outlet openings at the downstream end of the bores 8 on the lateral surface of an imaginary Rotationshyperboloids. Drop-loaded fluid 9 from the in Fig. 4 right section of the mixing chamber 7 thus exits on the left side of the nozzle orifice 40, wherein the bores 8, however, are guided past the central axis 16. The axes 44 of the individual beams or the associated holes 8 are so twisted about the main longitudinal axis 16 and inclined in two planes to this main longitudinal axis 16, the individual beams 18 can propagate largely without interaction with each other in the gas space 42.

Of course, it may be useful to attach the baffle plate 11, for which different geometries in question, to the mixing chamber inlet part 20. For the primary atomization of the liquid in the mixing chamber 7, many concepts can be used in principle come. When decoupling the baffle 11 from the nozzle exit part there is again the possibility to arrange a central bore, not shown here. Furthermore, the conical front portion 19 of the multi-hole nozzle can be manufactured with the individual nozzle holes as the nozzle center body 50, which is inserted into a conical cap 52 same opening angle, which is schematically in Fig. 5 is shown. The conical nozzle central body 50 can then also represent a configuration in the manner of a helical bevel gear, wherein cutouts 54 replace the holes 8. This offers in particular production engineering but also procedural advantages. Of course, this multi-hole nozzle 43 according to Fig. 4 be equipped with a nozzle hood 23 an annular gap nozzle. In addition, an in Fig. 4 not shown, the annular gap nozzle outside surrounded Schleierluftdüse be provided.

In the multi-hole nozzle 43 according to Fig. 4 the liquid 1 is thus injected in a known manner into a mixing chamber 7 or divided on a baffle 11 into relatively large primary drops 9. In the same mixing chamber 7 and compressed air is introduced. This compressed air takes the primary droplets with it, and in the strongly accelerating passage through the outlet channels 8, the primary droplets are divided into smaller droplets. Again, the outlet channels 8 are arranged around the main axis 16, that the focus of the individual droplets 18 is approximately in the nozzle exit plane, as in the bundle nozzle 45 according to Fig. 3 was described in detail unlike Fig. 3 but still within the front section 19 or mouthpiece. At the in Fig. 5 shown embodiment of a nozzle orifice 49 outlet channels are arranged on the type of grooves on a helical bevel gear whose smaller diameter is located in the nozzle outlet opening and wherein the fluid exits through the channels between the adjacent teeth. And the said channels are according to Fig. 5 have been produced by cutouts 54 on the conical nozzle central body 50, as in the manufacture of helical bevel gears of the Case is. After placing the cone-shaped outer body 52 channels are then formed with a closed cross-section.

In such a multi-hole nozzle 43, as described Fig. 4 and Fig. 5 has been described, the arrangement of an annular gap secondary atomizing nozzle 23 or a Schleierluftdüse no problems.

If the holes 8 of the multi-hole nozzle are of circular design, it may be advantageous to insert short tubes into the outlet holes 8. As with the bundle nozzles, a narrow annular gap configuration for the supply of the gap air can be achieved in this way. In this case, the nozzle hood 23 of the annular gap nozzle would then have passage openings adapted to the outer dimensions of the inserted tubes in its front surface.

LIST OF REFERENCE NUMBERS

1

liquid to be atomized

2

central lance tube for the liquid supply to the head of the bundle nozzle or to the multi-hole nozzle

3

Two-substance multi-hole nozzle according to the prior art

4

Lance tube for the supply of compressed gas to the two-fluid nozzle

5

Holes for the introduction of compressed gas into the mixing chamber

6

Compressed gas, in particular compressed air

7

Mixing chamber of the two-fluid nozzle

8th

Nozzle outlet holes of a multi-hole nozzle

9

Binary mixture of compressed gas and liquid drop in the mixing chamber

10

Bore for the introduction of the liquid into the mixing chamber

11

Impact surface for the primary fragmentation of the liquid

12

Liquid film on a central covering nose

13

Large secondary drops that detach from the liquid film 12

14

Central lining nose

15

anvil

16

Main longitudinal axis of the multi-hole nozzle or bundle nozzle

17

recirculation vortex

18

Drop jet with fine droplets in the core and significantly larger edge drops, which arise from liquid films in the outlet holes 8 in the absence of a sufficiently strong gap air flow

19

Outlet part of the multi-hole nozzle, nozzle mouthpiece

20

Entry part of the mixing chamber

21

Top of the central plaque nose

22

Supply pipe for the high or medium pressure split air

23

annular die

24

Annular gap with a conical or star-shaped cross-section

25

Annular gap air

26

Bunch nozzle according to the prior art

27

Holes for the supply of liquid to the individual nozzles

28

Mixing chamber inlet part for the liquid in the bundle nozzle

29

sheath air

30

Exit slit for the fog air

31

Large holes for the introduction of the atomizing pressure gas in the primary pressure chamber 32 of the bundle nozzle

32

Primary pressure chamber for the atomizing air of the bundle nozzle

33

From annular gap 30 leaking veil air

34

Secondary pressure chamber for the annular gap air of the bundle nozzle

35

Throttling element for reducing the pressure of the annular gap air or for the separation of the primary pressure chamber 32 from the secondary pressure chamber of the compressed gas

36

Single nozzles of the bundle nozzle

37

Axes of the individual nozzles

38

Tapered front surface of a prior art bunching die

39

Coverings on a bundle nozzle according to the prior art

40

Mouth region of a bundle nozzle or a multi-hole nozzle according to the invention

41

Nozzle carrier body according to the invention

42

Flue gas into which is sprayed

43

Multi-hole nozzle according to the invention

44

Axes of the holes in the multi-hole nozzle

45

Bundle nozzle according to the invention

46

central nozzle

47

Nozzles on a ring around the central nozzle

α

Mean jet opening angle of the bundle nozzle or the multi-hole nozzle

Claims (15)

1. Multi-hole or cluster nozzle having at least one mixing chamber for creating a gas/droplet mixture and several outlet openings for said gas/droplet mixture arranged downstream of the at least one mixing chamber, wherein the central longitudinal axes (44) of at least two of the outlet openings (56) are aligned askew relative to one another, where a distance between the central longitudinal axes (44) of these outlet openings (56) and the main longitudinal axis (16) of the nozzle (43; 45) is initially reduced when seen in the outflow direction, without intersecting the central longitudinal axis (16) and increases again after passing through a minimum distance.
2. Multi-hole or cluster nozzle according to Claim 1, characterized in that the at least two outlet openings (56) are arranged in a ring around the central longitudinal axis (16) of the nozzles (43; 45).
3. Multi-hole or cluster nozzle according to Claim 1 or 2, characterized in that the central longitudinal axes (44) of the at least two outlet openings (56) are, when seen on a plane containing the main longitudinal axis (16) of the nozzle (43; 45), arranged at the same angle to the main longitudinal axis (16) of the nozzle (43; 45).
4. Multi-hole or cluster nozzle according to one of the preceding claims, characterized in that the central longitudinal axes (44) of the at least two outlet openings (56) are inclined in the same direction around the main longitudinal axis (16) of the nozzle (43; 45) relative to a circumferential direction.
5. Multi-hole or cluster nozzle according to one of the preceding claims, characterized in that the central longitudinal axes (44) of the at least two outlet openings (56) are on the outer surface of an imaginary rotation hyperboloid.
6. Multi-hole or cluster nozzle according to one of the preceding claims, characterized in that the nozzle jets generated by the at least two outlet openings (56, 58) can spread out largely without interaction between them in a process chamber downstream of the outlet openings (56, 58).
7. Multi-hole or cluster nozzle according to one of the preceding claims, characterized in that a central outlet opening (58) on the main longitudinal axis (16) of the nozzle (45) is provided, about which opening the at least two further outlet openings (56) are arranged in a ring.
8. Multi-hole or cluster nozzle according to Claim 7, characterized in that the central longitudinal axes (44) of the at least two further outlet openings (56) are inclined in the same direction around the main longitudinal axis (16) of the nozzle relative to a circumferential direction in order to generate a twist about the main longitudinal axis (16) of the nozzle.
9. Multi-hole or cluster nozzle according to at least one of the preceding claims, characterized in that an annular gap nozzle is provided surrounding the outlet openings (56, 58) and subjected to compressed air.
10. Multi-hole or cluster nozzle according to Claim 9, characterized in that the outlet openings (56) are provided inside a nozzle mouthpiece (19; 49) surrounded by an annular gap nozzle.
11. Multi-hole or cluster nozzle according to one of the preceding claims, characterized in that a nozzle support element (41) is provided on which are arranged several individual nozzles (46, 47) projecting from the nozzle support element (41) in the outflow direction, where the individual nozzles (46, 47) are surrounded at least at the level of their outlet openings by an annular gap nozzle hood (23), such that an annular gap is formed between the individual nozzles (46, 47) and the annular gap nozzle hood (23) at the level of the outlet openings.
12. Multi-hole or cluster nozzle according to Claim 11, characterized in that a central nozzle (46) with an outlet opening on the main longitudinal axis (16) of the nozzle and at least two further individual nozzles (47) surrounding the main longitudinal axis (16) of the nozzle in annular form are provided, where an end face of the annular gap nozzle hood (23) has one or more annular gap openings, such that at the level of the outlet openings a distance between an outer circumference of the individual nozzles (46, 47) and the individual nozzles (46, 47) adjacent to the annular gap opening(s) or the outer circumference is substantially identical.
13. Multi-hole or cluster nozzle according to one of the preceding Claims 9 to 12 where dependent on Claim 9, characterized in that the annular gap nozzle is surrounded by an annular sheath air nozzle (29).
14. Multi-hole or cluster nozzle according to one of the preceding claims, characterized in that a nozzle support element (41) is provided on which are arranged several individual nozzles (46, 47) projecting from the nozzle support element (41) in the outflow direction, where the individual nozzles (46, 47) are arranged on a front side of the nozzle support element (41) that is generally concave when viewed in the outflow direction.
15. Multi-hole or cluster nozzle according to at least one of the preceding claims, characterized in that the outlet openings are provided in a nozzle mouthpiece (49), where the nozzle mouthpiece (49) has a central nozzle element (50) with conical outer surface and a hood (52) surrounding the central nozzle element (50) and contacting its outer surface in some sections, and where the central nozzle element (50) and/or the hood (52) have milled-out areas (54) ending at the outlet openings and forming nozzle channel grooves.

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