EP1986788B1 - Two-component nozzle with secondary air nozzles arranged in circular form - Google Patents

Description

The invention relates to a two-fluid nozzle with a main nozzle, with a mixing chamber and a nozzle connected to the mixing chamber and arranged downstream of the mixing chamber, wherein secondary air nozzles are provided, which open in the region of the nozzle mouth annular.

US 1,451,063 shows a burner nozzle, in which a liquid fuel is introduced by means of a centrally arranged feed nozzle in a mixing space. The mixing chamber is circular-cylindrical and widens in three successive stages up to an outlet opening. In the region of the individual stages of the mixing chamber and in the region of the nozzle mouth, annular secondary air nozzles open in each case. The secondary air nozzles are formed as cylindrical bores and arranged so that they do not intersect a central longitudinal axis of the mixing chamber.

EP 0 205 739 A1 describes a nozzle for feeding mud. In the area of the nozzle mouth open cylindrical nozzle holes for introducing a Zerteilermediums.

In many process plants, liquids are distributed in a gas. It is often of crucial importance that the liquid is sprayed in fine drops as possible. 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 significantly dependent on the average droplet size. But many times it is by no means sufficient that the mean droplet size falls 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 subsequent components, eg fabric filter bags or fan blades, are deposited and lead to malfunction due to incrustations or corrosion.

To spray liquids finely, either high-pressure single-fluid nozzles or medium-pressure two-fluid nozzles are used. An advantage of two-component nozzles is that they have relatively large flow cross-sections, so that even coarse particle-containing liquids can be sprayed.

The presentation of the Fig. 1 shows by way of example a two-way nozzle 3 according to the prior art which is substantially symmetrical with respect to the axis 24.

The liquid to be sprayed 1 is introduced via a central lance tube 2 at the constriction 10 in the mixing chamber 7. The compressed gas 15 is supplied via an outer lance tube 4 of an annular chamber 6, which surrounds the mixing chamber in an annular manner; over a certain number of holes 5, the compressed gas is introduced into the mixing chamber 7. In this mixing chamber, a first division of the liquid takes place in drops, so that here a drop-containing gas 9 is formed. Also at the outlet from the mixing chamber 7 there is a constriction 14. At the bottleneck 14, a divergent outlet part 26 connects, which ends with the nozzle orifice 8. The droplet-containing gas stream 9 formed in the mixing chamber 7 is greatly accelerated in the convergent-divergent nozzle, also called the Laval nozzle, so that here a further division of the droplets is effected.

Two-substance nozzles with a single exit bore of conventional design suffer from the property that the jet 21 emerging from the nozzle of droplets and atomizing air has only a small opening angle α. This has the consequence that relatively large distances or large containers are required for the drop evaporation.

A fundamental problem with these nozzles results from the fact that the walls in the mixing chamber 7 are wetted with liquid. The liquid which wets the wall in the mixing chamber is driven by the shear stress and pressure forces as liquid film 20 to the nozzle mouth. It is tempting to assume that the walls are blown dry towards the nozzle mouth due to high flow velocities of the gas phase and that only very fine droplets are formed from the liquid film.

However, the inventor's theoretical and experimental work has shown that liquid films on walls can still exist as stable films without dripping even when the gas flow which drives the liquid film to the nozzle orifice is supersonic reached. And this is also the reason why it is possible to use liquid film cooling in rocket thrusters. The film flow is particularly critical in the spraying of highly viscous liquids which simultaneously have a high surface tension, for example of glycol in refrigeration dryers of natural gas pumping stations or of solid suspensions in spray absorbers.

The liquid films, which are driven by the gas flow to the nozzle orifice 8, can even roam around a sharp edge on the nozzle orifice due to the adhesive forces; they then form on the outside of the nozzle mouth a water bead 12, see Fig. 1 , From this water bead to dissolve edge drops 13 whose diameter is a multiple of the average droplet diameter in the jet core. Although these large edge drops contribute only a small mass fraction to the overall drop load, they are ultimately determinative of the dimensions of the container in which, for example, the temperature of a gas is to be lowered by evaporative cooling from 350 ° C to 120 ° C, without causing an entry from drops to downstream components such as blowers or fabric filters.

The not previously published German patent application DE 10 2005 048 489.1 The same inventor relates to a two-fluid nozzle, in which the formation of large edge drops is reliably prevented by an annular gap atomization. Fig. 2 shows a corresponding two-fluid nozzle with annular gap atomization. In the illustrated variant, the annular gap air, also referred to here as secondary air, is branched off via bores 19 directly from the annular chamber 6. But even this type of nozzle suffers from the property to produce a relatively slender beam 21, with an opening angle α of about 15 °. That such nozzles in principle by a Schleieduft- or blocking air ring 25 and a Schleierluft- or Sperrluftdüse 23 may be enclosed, is known. The main difference between the Blocking air 11 and the annular gap air is that the total pressure of the exiting from the annular gap 16 annular clearance air of the order of magnitude coincides with the pressure of the pressurized gas 15 for the atomization, while the pressure of the sealing air 11 is usually smaller by one or two orders of magnitude.

Compressed gas exits the annular gap 16 at high speed and ensures that a liquid film on the wall of the nozzle mouth, in particular of the divergent outlet section, is drawn out to a very thin liquid lamella, which then decays into small drops. In this way, the formation of large drops of wall liquid films in the nozzle exit region can be prevented or reduced to an acceptable level and at the same time the fine droplet spectrum in the jet core can be obtained without the need to increase the pressure gas consumption of the two-fluid nozzle or the associated own energy demand. The annular air volume may be, for example, 10% to 40% of the total atomizing air amount. The total pressure of the air in the annular gap is advantageously 1.5 bar to 2.5 bar absolute. The total pressure of the air in the annular gap is advantageously so high that when it is expanded to the pressure level in the container, approximately sound velocity is achieved. The outlet opening is formed by means of a peripheral wall, whose extreme end forms an outlet edge and the annular gap is arranged in the region of the outlet edge. Conveniently, the annular gap between the exit edge and an outer annular gap wall is formed. Seen in the outflow direction, the annular gap wall edge is arranged after the trailing edge. Advantageously, the annular gap wall edge is arranged between 5% and 20% of the diameter of the outlet opening to the outlet edge. A pressure of the compressed gas supplied to the annular gap and a pressure of the compressed gas opening into the mixing chamber through the compressed gas inlet can be set independently of one another. The inlet bores 5 in the mixing chamber can be aligned tangentially to a circle about a central longitudinal axis of the nozzle be to create a spin in a first direction. Multiple inlet bores may be provided spaced from one another, and different inlet bores may be tangentially aligned to produce a twist in different directions, for example, opposing twist directions.

In the non-prepublished patent application DE 10 2006 0013190 is a two-fluid nozzle for wall-mounted installation described in which to avoid wall coverings a Hüll-, barrier or Schleierluftdüse and the wall area are heated in the vicinity of the nozzle. Incidentally, the nozzle described therein is analogous to the two-fluid nozzle according to DE 10 2005 048 489.1 designed.

All the two-fluid nozzles described above have in common that the opening angle of a spray jet generated is comparatively low, so that large distances are required for the drop evaporation.

With the invention, a two-fluid nozzle is to be provided with which a large opening angle of the spray jet can be achieved.

According to the invention, a two-substance nozzle is provided with a main nozzle, with a mixing chamber and a nozzle mouth arranged downstream of the mixing chamber, in which secondary air nozzles open out annularly in the area of the nozzle mouth and in which the secondary air nozzles between two components located in the area of the nozzle mouth Recesses are formed in at least one of the two opposing components in the region of the nozzle mouth.

By providing a ring of secondary air nozzles arranged in the area of the nozzle mouth or also surrounding the nozzle mouth, a nozzle jet with a substantially larger opening angle α of at least approximately 30 ° to 45 ° can be produced. From the secondary air nozzles Exiting compressed air jets act on the emerging from the nozzle jet of droplets and atomizing air and expand it. At the same time, without a continuous annular gap, the advantages of the annular gap atomization according to the German patent application DE 10 2005 048 489.1 are maintained and specifically the formation of large peripheral drops is prevented. The nozzle according to the invention is therefore characterized by a two-fluid nozzle with annular gap atomization according to the German patent application, not previously published DE 10 2005 048 489.1 By replacing the annular gap for the annular gap atomization by a ring of individual air nozzles, which surround the nozzle mouth. By enclosing this is meant that the individual secondary air nozzles are arranged in a circle around the nozzle mouth around and that at several secondary air nozzles whose outlet jets touch or even overlap in the region of the nozzle mouth, so that a continuous annular beam of secondary air surrounds the nozzle mouth. In this case, the imaginary projections of the secondary air bores in the plane of the nozzle mouth can overlap to form a closed, annular surface. Individual Sekundärluftdüsenbohrungen take their beginning so in the comparatively wide annular space outside the mixing chamber, but can in the further course in the direction of the nozzle mouth at this quite touch or even overlap. In addition to the already discussed overlapping of the projections of the extensions of the nozzle bores on the plane of the nozzle mouth secondary air holes can of course also be introduced so that they overlap already in the region of the outlet and in the region of the nozzle orifice, so that the wall of the nozzle mouth an annular, circumferential recess having. The nozzle according to the invention thus offers the possibility of providing an annular gap of variable width, depending on the diameter or arrangement of the secondary air bores. This is particularly important in the production of nozzle series or nozzle families, if one and the same body is to be provided with different annular gap widths. The nozzle according to the invention can thus have a geometric overlap have the secondary air holes in the mouth of the nozzle and either this overlap already takes place in the wall region of the nozzle mouth or only on an imaginary plane at the level of the nozzle mouth. However, in addition to the secondary air nozzles, an annular gap atomization may also be provided. By providing annularly arranged secondary air nozzles, a two-substance nozzle with internal mixing can be transformed by a transformation in the region of the nozzle mouth into a nozzle with a wide-angle jet.

In a further development of the invention, a main spraying direction of the secondary air nozzles is aligned into a main spray jet emanating from the nozzle mouth.

By such an orientation of the secondary air nozzles, they enter into the spray jet of the main nozzle and thereby widen it.

In a further development of the invention, the central longitudinal axes of the secondary air nozzles are arranged to a central longitudinal axis of the main nozzle at an angle β of 20 ° to 80 °.

In this way, the spray of secondary air nozzles receives both a component parallel to the central longitudinal axis of the main nozzle and a perpendicular thereto arranged component, which is mainly responsible for the expansion of the spray. Different expansions of the spray jet can be achieved by the variation of the angle β.

In a further development of the invention, the central longitudinal axes of the secondary air nozzles do not intersect the central longitudinal axis of the main nozzle.

By such a skewed arrangement of the central longitudinal axes of the secondary air nozzles, a particularly uniform widening of the spray jet can be achieved. With appropriate arrangement of the secondary air nozzles For example, a spray can be imparted to the spray jet of the main nozzle, which promotes widening of the spray jet.

In a further development of the invention, the secondary air nozzles are aligned tangentially to an imaginary circle concentric with the central longitudinal axis of the main nozzle.

In this way, a very effective widening of the spray jet with fine droplet atomization can be achieved. In the direction of the central longitudinal axis of the main nozzle, the central longitudinal axes of the secondary air nozzles appear as tangents which rest on an imaginary circle concentrically surrounding the central longitudinal axis of the main nozzle. Since the secondary air nozzles moreover enclose an angle of less than 90 ° with the central longitudinal axis of the main nozzle, they thus touch an imaginary circular cylinder which concentrically surrounds the central longitudinal axis of the main nozzle. Advantageously, this imaginary circle has a radius which is between 30% and 80% of the radius of the spray jet of the main nozzle at the level of the circle. Such an orientation of the secondary air nozzles results in a significant widening of the spray jet with fine droplet atomization. If one thus considers the imaginary circle on which the projection of the central longitudinal axes of the secondary air nozzles lie tangentially, and especially the plane in which this circle lies, then this plane with the outer boundary of the main spray jet forms a circular section line with a spray jet radius. The imaginary circle then has a radius which is between 30% and 80% of this spray radius. Advantageously, the imaginary circle is arranged downstream of the nozzle mouth or main nozzle. The contact points of the central longitudinal axes of the secondary air nozzles are thus at an imaginary circular cylinder about the central longitudinal axis of the main nozzle downstream of the nozzle mouth.

In a further development of the invention, the secondary air nozzles open upstream of the nozzle mouth of the main nozzle in the outflow from the mixing chamber to the nozzle mouth.

It has proven to be advantageous if the secondary air nozzles open directly in front of the nozzle mouth in the discharge channel. It may be advantageous that touch the mouths of the secondary air nozzles at the entrance to the discharge or partially overlap.

In a further development of the invention, a separate air supply line is provided to the secondary air nozzles.

In this way, the amount of air and the velocity of the air exiting the secondary air nozzles can be adjusted separately and used, for example, to set a desired spray jet angle. For this adjustment means are then required for setting an air pressure at the secondary air nozzles.

In a further development of the invention, the secondary air nozzles are in flow communication with a feed line for compressed gas, wherein this feed line is also in flow communication with the mixing chamber.

A simple construction of the nozzle according to the invention results when the air required for the secondary air nozzles from the supply line for compressed gas of the main nozzle is shown. For this purpose, the secondary air nozzles can advantageously be connected to an annular space surrounding the mixing chamber. In this way, the two-fluid nozzle according to the invention can be constructed very compact.

In a further development of the invention, the nozzle mouth is surrounded by an annular gap, wherein the annular gap can be acted upon with compressed air.

By providing such an additional annular gap atomization, water droplets at the nozzle mouth, which originate from a liquid film occupying the wall of the outflow channel, can be drawn out into liquid lamellae and atomized into fine droplets. An additional annular gap atomization can be particularly advantageous if the individual secondary air nozzles do not touch or overlap at the edge of the outflow channel.

In a further development of the invention, it is provided that, starting from the mixing chamber, an outflow channel initially narrows continuously and then, starting from a constriction in the outflow channel, widens continuously again towards the nozzle mouth.

In this way, the two-substance mixture passed through the outflow channel in the convergent-divergent nozzle is greatly accelerated and a fine droplet distribution in the spray jet can be achieved. The outflow channel can be designed and the pressure of the liquid and of the compressed gas adjusted in such a way that in the outflow channel at least partially supersonic speed is reached.

In a further development of the invention, an additional, the nozzle mouth annular surrounding Schleierluftdüse is provided.

Such a Schleierluftdüse or Hüllluftdüse may be provided in addition to the annular gap for the Annularspaltverdüsung and is subjected to lower pressure air than is required for the Annularspaltverdüsung.

Fig. 1

eine Zweistoffdüse nach dem Stand der Technik,

Fig. 2

eine Zweistoffdüse mit Ringspaltverdüsung und Schleierluftdüse gemäß der nicht vorveröffentlichten Anmeldung DE 10 2005 048 489.1 ,

Fig. 3

eine erste Ausführungsform einer erfindungsgemäßen Zweistoffdüse,

Fig. 4

eine zweite Ausführungsform einer erfindungsgemäßen Zweistoffdüse,

Fig. 5

eine Ansicht auf die Ebene V-V der Fig. 4 zur Verdeutlichung der Anordnung der Sekundärluftdüsen bei der Zweistoffdüse der Fig. 4,

Fig. 6 bis 12

verschiedene Ansichten einer dritten Ausführungsform einer erfindungsgemäßen Zweistoffdüse,

Fig. 13

eine Schnittansicht einer vierten Ausführungsform einer erfindungsgemäßen Zweistoffdüse,

Fig. 14

eine Schnittansicht eines den Düsenauslass der Zweistoffdüse der Fig. 13 definierenden Bauteils und

Fig. 15

eine Ansicht des Bauteils der Fig. 14 von unten.

Further features and advantages of the invention will become apparent from the claims and the following description taken in conjunction with the drawings. Individual features of the different, illustrated in the drawings embodiments of the invention can be combined with each other in any way, without the scope of the To exceed invention. Specifically, the characteristics of in Fig. 2 shown two-fluid nozzle in any way with the in Fig. 3 . 4 and 5 combine illustrated nozzles, without exceeding the scope of the invention. In the drawings show:

Fig. 1

a two-fluid nozzle according to the prior art,

Fig. 2

a two-fluid nozzle with annular gap atomization and Schleierluftdüse according to the not previously published application DE 10 2005 048 489.1 .

Fig. 3

A first embodiment of a two-substance nozzle according to the invention,

Fig. 4

A second embodiment of a two-substance nozzle according to the invention,

Fig. 5

a view on the level VV the Fig. 4 to clarify the arrangement of the secondary air nozzles in the two-fluid nozzle of Fig. 4 .

6 to 12

various views of a third embodiment of a two-fluid nozzle according to the invention,

Fig. 13

a sectional view of a fourth embodiment of a two-fluid nozzle according to the invention,

Fig. 14

a sectional view of the nozzle outlet of the two-fluid nozzle of Fig. 13 defining component and

Fig. 15

a view of the component of Fig. 14 from underneath.

The sectional view of Fig. 3 shows a two-fluid nozzle 30 according to the invention, which has a concentrically arranged to a central longitudinal axis 32 of the nozzle feed tube 34 for liquid to be sprayed. The feed tube 34 merges into a frusto-conical constriction 36 and then into a cylindrical constriction 38, which is followed by a mixing chamber 40 which widens in the shape of a truncated cone. The mixing chamber is provided in its peripheral wall with inlet openings 42 for compressed gas. The inlet openings 42 are arranged in two, spaced apart along the outflow direction rings in the wall of the mixing chamber 40. The mixing chamber 40 is adjoined by an outflow channel 44, which ends at the nozzle mouth 46 and initially narrows continuously and then expands continuously again starting from a constriction 45. In the sectional view of Fig. 3 the boundary of the outflow channel thereby has a continuously curved shape in the outflow 44, the mixture formed in the mixing chamber 40 of gas and liquid, such as air and water, greatly accelerated and can reach supersonic speed in the divergent section.

Compressed gas is fed to the two-substance nozzle 30 via a compressed gas pipe 48 which surrounds the feed pipe 34 concentrically. The compressed gas is accordingly guided in the annular region between feed tube 34 and compressed gas tube 48. Starting from an annular space surrounding the mixing chamber 40, the compressed gas then passes through the inlet openings 42 into the mixing chamber 40. At the downstream end of the annular space 50, inlet openings of secondary air nozzles 52a, 52b are arranged, into which compressed gas according to the Fig. 3 indicated arrows 54 occurs. The secondary air nozzles 52 are formed as bores in a closure piece 56 which centrally carries the outflow channel 44 and at the upstream end of the outflow channel 44 provides a flange for receiving a, the mixing chamber 40 defining tubular component. The annulus 50 for the pressurized gas will also formed by the component 56, and at its upstream end, the component 56 is screwed to the compressed gas tube 48.

The secondary air nozzles 52a, 52b have central longitudinal axes 58a, 58b, which form an angle β with the central longitudinal axis 32 of the main nozzle defined by the outflow channel 44. The angle β is in the representation of Fig. 3 about 45 ° and can be between about 20 ° and about 80 °. The secondary air nozzles 52 a, 52 b open into the outflow channel 44 immediately upstream of the nozzle mouth 46. The central longitudinal axes 58 a and 58 b of the two illustrated secondary air nozzles 52 a, 52 b intersect downstream of the nozzle mouth 46 with the central longitudinal axis 32.

Furthermore, one, the nozzle mouth 46 annular surrounding Hüllluftdüse 66 is provided by means of a. Hüllluftohres 68 is formed. Through the Hüllluftrohr 68 compressed gas is supplied at a lower pressure than the mixing chamber 40 supplied compressed gas. The enveloping air surrounds the spray jet 64 annularly.

The sectional view of Fig. 4 shows a two-fluid nozzle 70 according to the invention according to a further embodiment of the invention. To the two-fluid nozzle 30 of the Fig. 3 identical parts are provided with the same reference numerals and will not be explained again.

In contrast to the two-fluid nozzle 30 of Fig. 2 In the two-fluid nozzle 70 four secondary air nozzles 72a, 72b, 72c and 72d are provided, wherein in the illustration of Fig. 3 only three secondary air nozzles 72a, 72b and 72d can be seen. In the view of Fig. 4 On the other hand, the orifices of the four secondary air nozzles 72a, 72b, 72c and 72d are indicated in an outflow channel 74 of the two-component nozzle 70. These openings are located directly above a nozzle mouth 76. To illustrate the arrangement of the secondary air nozzles 72a, 72b, 72c and 72d, the respective central longitudinal axes 78a to 78d are shown.

Based on the presentation of the Fig. 4 It can be seen that the central longitudinal axis 78a to 78d of the two-substance nozzle 72a to 72d are inclined on the one hand by the angle β to the central longitudinal axis 32 of the main nozzle, as already in FIG Fig. 3 can be seen. In addition, the central longitudinal axes 78a to 78d but are skewed to the central longitudinal axis 32 and lie tangentially to a circle which is arranged concentrically to the central longitudinal axis 32 of the main nozzle. The secondary air nozzles 72a to 72d thus impart a twist to the binary mixture emerging from the outflow channel 74 and thereby ensure that the spray jet widened to the spray angle α. By correspondingly adjusting the diameter of the secondary air nozzles, the nozzle bores can also be achieved in this case the confluence with the outflow channel 74 touch or partially overlap.

The lines of action of the secondary air jets are therefore not directed towards the central longitudinal axis 32 of the main jet, but they dive into this main jet at a suitable radius r ₁ , which is between 20% and 80% of the radius of the main beam at the relevant point. Also, the inclination angle β of the central longitudinal axes of the secondary air nozzles relative to the central longitudinal axis 32 of the main nozzle plays a significant role, wherein, as mentioned, here the angle range between 20 ° and 80 ° for this angle β is particularly advantageous.

The nozzle 30 according to the invention is thus characterized by a two-fluid nozzle with annular gap atomization according to the German patent application, not previously published DE 10 2005 048 489.1 By replacing the annular gap for the annular gap atomization by a ring of individual air nozzles, which surround the nozzle mouth. As shown in the dual-fluid nozzle 70, an annular gap atomization may be provided with the annular gap 80 in addition to the ring of secondary air nozzles.

A certain disadvantage of the nozzle according to the invention could be seen in the fact that the provision of secondary air requires additional energy. However, one should not overlook the fact that conventional two-fluid nozzles with a single nozzle mouth produce a very compact, slim droplet jet. In order to be able to realize the drop evaporation in a similarly short time or on a comparably short path, as in the novel nozzle, it must be sprayed much finer in a slender jet. Of course, this is also associated with a substantial increase in energy consumption. And competing concepts of the two-fluid nozzles, which have a plurality of nozzle holes instead of a single nozzle mouth, also called bundle nozzles, and thus achieve a large jet angle, suffer from the disadvantage that the small exit holes are clogged relatively quickly, especially in the spray of solid suspensions. Furthermore, caking readily occurs on the nozzle body between the nozzle bores. Both effects can contribute to a significant disturbance of the atomization by promoting the formation of large drops. In addition, the controllability of bundle nozzles is limited and it is comparatively complicated to surround bundle nozzles with sealing air or enveloping air, which would help avoid formation of deposits on the nozzle body between the bores.

In contrast to the two-fluid nozzle 30 of Fig. 3 is the two-fluid nozzle 70 of Fig. 4 in addition to an annular gap 80 which is directly adjacent to the outflow channel 74 and provided for annular gap atomization for the purpose of avoiding coarse liquid droplets on the nozzle mouth 76, provided with a Schleierluftdüse 82 which surrounds the annular gap 80 annular and for the supply of compressed gas at a lower pressure than is provided in the mixing chamber 40 and the annular gap 80.

The presentation of the Fig. 5 shows a view of the two-fluid nozzle 70 from below and approximately at the level of in Fig. 4 Dashed line VV. In the presentation of the Fig. 5 It can be seen that the central longitudinal axes 78a to 78d abut tangentially on an imaginary circle with the radius r ₁ approximately at the level of the plane VV and therefore downstream of the nozzle mouth 76. The radius of this circle r ₁ amounts to about 50% of the radius of the spray jet of the main nozzle placed on this, the in Fig. 4 through the section line of the dashed plane VV and the likewise indicated by dashed lateral surface 84 of the main spray in Fig. 4 is defined. The radius r ₁ may be between 30% and 80% of the radius of the principal ray at the point concerned. In other words and as in Fig. 5 can be seen, the radius r ₁ between the radius of the nozzle mouth 76 and the radius of a constriction 86 in the discharge channel 74. The central longitudinal axes 78a to 78d thus tangentially touch an imaginary circular cylinder, which is aligned concentrically to the central longitudinal axis 32 of the main nozzle and the radius between the radius of the nozzle mouth 76 and the radius of the constriction 86 in the convergent-divergent-shaped outflow 74 of the two-fluid nozzle 70 is located. The contact point of the central longitudinal axes 78a to 78d at this imaginary circular cylinder can be located downstream of the nozzle mouth, with a corresponding design of the nozzle but also quite at the level of the nozzle mouth itself or even upstream thereof.

The presentation of the Fig. 6 shows a two-fluid nozzle 90 according to the invention with a nozzle body 92, the one in Fig. 6 has invisible through hole, which forms a nozzle mouth 94 at its exit from the nozzle body 92. As already in the Fig. 6 can be seen and as will be explained in more detail below, the shape of the nozzle mouth 94 from a circular shape. This is caused by nozzle bores of four secondary air nozzles opening in the area of the nozzle mouth.

The presentation of the Fig. 7 shows the two-fluid nozzle 90 in a side view, wherein additionally indicated by dashed lines nozzle holes of the secondary air nozzles. Specifically, nozzle bores 96, 98, 100 and 102 are indicated by dashed lines, which are all arranged at an angle of approximately 45 ° to a central longitudinal axis of the nozzle and open into an outflow channel 104 in the region of the nozzle orifice 94.

The presentation of the Fig. 8 shows a view of the two-fluid nozzle 90 from below, ie from the side of the nozzle mouth 94 ago. Good to see the four nozzle holes 96, 98, 100 and 102 and their staggered to a coordinate system through the central longitudinal axis arrangement. The nozzle bores 96, 98, 100 and 102 are thereby arranged tangentially to an imaginary circle about the central longitudinal axis of the nozzle and do not intersect the central longitudinal axis. In Fig. 8 Furthermore, the detail D is shown enlarged, the mouth of the nozzle bores 96, 98, 100 and 102 in the region of the nozzle mouth show, the ellipses of the detail D, which indicate the mouth area, are only visible when in the nozzle body 92 first the nozzle holes 96, 98, 100 and 102 of the secondary air nozzles are introduced before the outflow channel 94. From the detail D it can be seen that the orifices of the nozzle bores 96, 98, 100 and 102 touch each other and thereby form a ring-like configuration as a whole around the central longitudinal axis of the two-substance nozzle. During operation, the secondary air emerging from the nozzle bores 96, 98, 100 and 102 thus forms an annular air jet which surrounds the spray jet emerging parallel to the central longitudinal axis. It is thereby ensured that a fluid film resting against the wall of the outflow channel 104 and driven through the flow towards the nozzle mouth 94 is detected over the entire circumference of the outflow channel 104 by secondary air from one of the nozzle bores 96, 98, 100 or 102, is pulled out to a thin liquid lamella at the nozzle mouth 94 and atomized into fine droplets.

The presentation of the Fig. 9 shows a sectional view taken along the line AA in Fig. 7 , Good to see the central through-hole of the nozzle and the nozzle holes 96, 98, 100 and 102 of the secondary air nozzles. The nozzle bores 96, 98, 100 and 102 intersect at the level of the cutting plane AA, each with a blind hole 106, the blind holes 106 emanating from an outer periphery of the nozzle, as well as in Fig. 6 can be seen, and are provided for the insertion of throttle screws to adjust a free cross section of the nozzle bores 96, 98, 100 and 102 can.

The presentation of the Fig. 10 shows a view of the two-fluid nozzle 90 according to the invention from the side of the nozzle mouth 94 forth and indicates the course of a section line BB. The cutting line BB initially runs centrally through the nozzle bore 102, bends vertically at the height of the central longitudinal axis. passes through the discharge channel 94 and then bends at the level of the center of the nozzle bore 98 again at right angles.

The presentation of the Fig. 11 shows the sectional view along the line BB. Good to see the course of the nozzle bores 102, 98, which initially extend parallel to a central longitudinal axis of the two-fluid nozzle 90, after passing through the respective associated blind hole 106 bend by 45 °, and then finally open in the region of the nozzle mouth 94 in the outflow channel 104. The nozzle holes 98, 102 and of course the in Fig. 11 unrecognizable nozzle bores 96, 100 start from an annular space 108, which in the Fig. 12 is shown and formed by the insertion of a mixing chamber 110 into the nozzle body 92. In this annulus 108 pressurized gas is introduced, which then enters through a first holes 112 in a mixing chamber 114 and on the other hand into the nozzle bores 96, 98, 100, 102 of the secondary air nozzles.

Also on the basis of Fig. 12 the mouth of the nozzle bores in the region of the nozzle mouth 94 can be seen, this one of the circular cylindrical Shape of the outflow channel 104 give a different shape.

The presentation of the Fig. 13 shows a sectional view of a two-fluid nozzle 120 according to the invention according to a fourth embodiment of the invention. In manufacturing terms, the obliquely introduced to the central longitudinal axis of the nozzle nozzle holes in the 3, 4, 5 and 6 to 12 illustrated two-fluid nozzles 30, 70 and 90 problematic. In the two-fluid nozzle 120 of the Fig. 13 Therefore, another possibility was chosen to realize a arranged in the region of the nozzle mouth ring of secondary air nozzles.

The two-fluid nozzle 120 has a feed tube 122 through which liquid to be sprayed is supplied to the nozzle. The feed tube 122 is surrounded by a concentric compressed gas tube 124, which in turn is surrounded concentrically by a Schufierfuftrohr 126. It has already been explained that the veiling air is supplied at a substantially lower pressure than the compressed gas used for atomization. For example, the pressure of the compressed gas between 1 bar and 1.5 bar are absolute, the supplied air would then supplied, for example, with an absolute pressure of about 40 mbar to 80 mbar. The provision of fog air essentially serves to avoid incrustations in the region of the nozzle mouth. The compressed gas tube 124 has a frusto-conical component 130 which tapers toward a nozzle mouth, and the veiled air tube 126 also runs in the form of a truncated cone toward the nozzle mouth 128 and essentially parallel to the component 130.

The feed tube 122 is extended by means of a mixing chamber component 132, which is provided with a plurality of compressed gas bores 134, 136, 138. The compressed gas bores 134, 136, 138 are each arranged at an angle of about 45 ° to a central longitudinal axis of the nozzle, wherein pressurized gas is thereby introduced in the outflow direction into the mixing chamber and the extensions of the center axes of the pressure gas bores 134, 136, 138 intersect the central longitudinal axis of the two-substance nozzle 120.

As Fig. 13 it can be seen, in each case a plurality, for example four, compressed gas bores 134, 136, 138 are uniformly spaced and arranged around the circumference of the mixing chamber component 132 around. Seen in the outflow direction of the nozzle, a total of three rings with compressed gas bores 134, 136, 138 are arranged, all of which open into a mixing chamber 140. A cross-section of an annular gap between the pressurized gas tube 124 and the mixing chamber member 132 decreases downstream of each ring of pressurized gas bores 134, 136, 138.

At the transition from the feed pipe 122 to the mixing chamber component 132, a liquid nozzle 142 is provided, which initially clearly narrows the free cross section of the feed pipe 122 and then has a further cross-sectional constriction and protrudes with a nozzle pipe 144 into the mixing chamber 140. In the liquid nozzle 142 may optionally be provided a swirl insert 146. The nozzle tube 144 extends so far into the mixing chamber 140 in that the extensions of the pressure gas bores 134 coincide with the end of the nozzle tube 144. The pressure gas entering the mixing chamber 140 through the pressurized gas bores 134 thereby ensures that no larger drops of liquid can form at the end of the nozzle tube 144, but that any liquid adhering to the edge of the nozzle tube 144 is finely atomized. The provision of the fluid nozzle 142 is of considerable advantage, especially when the two-fluid nozzle 120 according to the invention is to be used over a large area of a liquid flow to be atomized.

Conventional two-fluid nozzles are usually designed for a narrow range of liquid flow. If the intended liquid flow range is undershot, conventional two-fluid nozzles tend to spit, since there is no entry at the inlet into the mixing chamber steady flow conditions give more. Instead, the liquid stream entering the mixing chamber migrates and the increased formation of large drops is the result. This is described by the term "spitting".

The liquid nozzle 142 provided at the entrance into the mixing chamber 140 thus serves to distinctly improve dynamics and the control range of the two-substance nozzle 120. At low liquid flow, the liquid tends to drip instationary when entering the mixing chamber 140, which ultimately leads to unsteady atomization, the so-called spitting of the nozzle and a poor part-load behavior. As a first remedy, the liquid nozzle 142 is now provided, the nozzle tube 144 projects into the mixing chamber 140. As a second measure, the first ring of the pressure gas bores 134 is arranged such that the liquid emerging from the nozzle tube 144 is entrained without intermediate storage by the compressed gas provided for the atomization. For this purpose, the pressure gas bores 134 are arranged in the, the liquid nozzle 142 at the inlet to the mixing chamber 140 closest bore ring so that the incoming compressed gas is directed to the mouth of the liquid nozzle 142.

The mixing chamber member 132 is inserted axially with its downstream end into an outlet member 148, which forms an outflow channel 150 and extends from the end of the mixing chamber 140 to the nozzle mouth 128. The mixing chamber 140 expands in the frustoconical direction, as viewed in the flow direction, in order to constrict again at the end of the mixing chamber component 132 through the outlet component 148 in the form of a truncated cone. The subsequent to the mixing chamber 140 outflow 150 first narrows, then passes into a circular cylindrical constriction, to then expand again to the nozzle mouth 128 out. The two-fluid nozzle 120 is accordingly designed as a convergent divergent nozzle or Laval nozzle. At least in the divergent Area of the outflow channel 150 reaches the compressed gas-liquid mixture sonic velocity.

The exit member 148 is provided at its upstream end with an annular flange 152 in which a plurality of through holes 154 are provided evenly spaced from each other. The annular flange 152 holds the outlet component 148 between the compressed gas tube 124 and the component 130 on the one hand and, with the through holes 154 on the other, ensures that secondary air can enter into a gap between the component 130 and the outlet component 148. Starting from this intermediate space, the pressurized gas then flows as so-called secondary air between the component 130 and the downstream end of the outlet component 148 in order to hit the spray jet in the area of the nozzle mouth 128 at the downstream end of the outlet channel 150.

As Fig. 13 can be seen, the outlet member 148 and the component 130 in the region of the nozzle mouth 128 are not adjacent to each other, so that secondary air can enter over the entire circumference of the discharge channel 150 in the region of the nozzle mouth. In order to impart a twist to the secondary air emerging in the region of the nozzle mouth 128 and thereby to expand the spray jet of the two-substance nozzle 120, cutouts 156 are provided at the downstream end of the outlet component 148. These cutouts 156 each form the upper portion of a nozzle channel and are in Fig. 15 to recognize more precisely. The secondary air passing between the component 130 and the outlet component 148 is thus channeled and aligned by the cutouts 156, in order then to strike the spray jet from the outflow channel 150 in the area of the nozzle mouth 128.

Based on the representations of FIGS. 14 and 15 the position of the cutouts can be seen more precisely. Specially based on the Fig. 15 It can be seen that the cutouts 156 with their central axis tangential to a imaginary circle about the central longitudinal axis of the two-fluid nozzle 120 are aligned. The spray jet at the nozzle mouth 128 is thereby subjected to a twist and expands. Since the outlet component 148 is manufactured separately and the nozzle channels are formed by means of the cutouts 156 only after the onset of the outlet component 148 into the component 130, the production of the two-component nozzle 120 is considerably facilitated. In addition or as an alternative to the cutouts 156 in the outflow component 148, the component 130 can also be provided with cut-outs forming nozzle ducts. Accordingly, the two-substance nozzle 120 according to the invention has a combination of nozzle bores opening at the nozzle mouth 128 with a circumferential annular gap.

An annular gap and secondary air nozzle bores or secondary air nozzle channels can thus be produced by milling on the outside of the conical exit component 148. Additionally or alternatively, the annular gap and the Sekundäluffdüsenbohrungen can also be generated by milling on the inside of the likewise conical outer body, so the component 130. If the outlet part 148 is brought into contact with the inside of the component 130, no continuous annular gap is formed any more, but only discrete nozzle channels.

The preparation of the slender secondary air nozzle holes in the two-fluid nozzle 30, 70 and 90 is costly and must be made for example by means of spark erosion. The spark erosion also allows, for example, to deviate from cylindrical holes. In contrast to this, the cutouts 156 on the outlet component 148 can be produced comparatively inexpensively by means of shaped cutters, for example as a rectangular groove or as a semicircular groove. But it is quite possible also an arbitrary different geometry of these cutouts, such as a wavy shape. By a suitable spacing of the conical outer body, that is, the component 130, relative to the central nozzle exit part 148 can here to simple A combination of annular gap and Sekundärluftdüsenbohrungen be effected.

Instead of providing the milling grooves 156 in the outlet component 148, the outlet component 148 and the conical outer body, that is to say the component 130, could again be combined to form a single, cast component, given a corresponding further development of precision casting methods.

Claims (16)

1. Two-component nozzle with a main nozzle with a mixing chamber (40) and a nozzle orifice (46; 76) connected to the mixing chamber (40) and positioned downstream thereof, wherein secondary air nozzles (52a, 52b; 72a, 72b, 72c, 72d) are provided and issue in annular manner in the vicinity of the nozzles orifice (46; 76), characterized in that the secondary air nozzles are formed between two component parts lying opposite one another in the vicinity of the nozzle orifice by means of recesses in at least one of the two component parts lying opposite one another in the vicinity of the nozzle orifice.
2. Two-component nozzle according to claim 1, characterized in that nozzle holes of the secondary air nozzles overlap in the vicinity of the nozzle orifice.
3. Two-component nozzle according to claim 1 or 2, characterized in that a main spraying direction of the secondary air nozzles (52a, 52b; 72a, 72b, 72c, 72d) is directed into a main spray jet emanating from the nozzle orifice (46; 76).
4. Two-component nozzle according to at least one of the preceding claims, characterized in that median longitudinal axes of the secondary air nozzles (52a, 52b; 72a, 72b, 72c, 72d) are arranged at an angle (β) of 20° to 80° to a median longitudinal axis (32) of the main nozzle.
5. Two-component nozzle according to at least one of the preceding claims, characterized in that median longitudinal axes of the secondary air nozzles (52a, 52b; 72a, 72b, 72c, 72d) do not intersect the median longitudinal axis (32) of the main nozzle.
6. Two-component nozzle according to at least one of the preceding claims, characterized in that the secondary air nozzles (72a, 72b, 72c, 72d) are oriented tangentially to an imaginary circle concentric to the median longitudinal axis (32) of the main nozzle, wherein in particular the imaginary circle has a radius (r₁) between 30% and 80% of the radius of the main jet level with the circle.
7. Two-component nozzle according to claim 6, characterized in that the circle is downstream of the nozzle orifice (76) of the main nozzle.
8. Two-component nozzle according to at least one of the preceding claims, characterized in that the secondary air nozzles (52a, 52b; 72a, 72b, 72c, 72d) upstream of the nozzle orifice (46; 76) of the main nozzle issue into an outflow channel (44; 74) from the mixing chamber (40) to the nozzle orifice (46; 76).
9. Two-component nozzle according to at least one of the preceding claims, characterized in that a separate supply air line to the secondary air nozzles is provided, wherein adjusting means are provided for adjusting an air pressure at the secondary air nozzles.
10. Two-component nozzle according to at least one of the preceding claims, characterized in that the nozzle orifice (46; 76) is surrounded by an annular clearance (80) to which pressure gas can be supplied.
11. Two-component nozzle according to at least one of the preceding claims, characterized in that starting from the mixing chamber (40), an outflow channel (44; 74) initially continuously narrows and then, starting from a narrow point (45; 86) then continuously widens up to the nozzle orifice (46; 76).
12. Two-component nozzle according to claim 11, characterized in that during operation of the nozzle a two-component mixture reaches supersonic speed at least in sections of the outflow channel (44; 74).
13. Two-component nozzle according to at least one of the preceding claims, characterized in that an additional screen air nozzle (82) is provided that surrounds the nozzle orifice (76) in an annular manner.
14. Two-component nozzle according to at least one of the preceding claims, characterized in that a liquid nozzle (142) is provided at the entrance to the mixing chamber.
15. Two-component nozzle according to claim 14, characterized in that the liquid nozzle (142) has a nozzle tube (144) extending into the mixing chamber (140).
16. Two-component nozzle according to claim 14 or 15, characterized in that pressure gas holes (134) are so positioned for the introduction of pressure gas into the mixing chamber (140) that pressure gas is directed onto an opening of the liquid nozzle (142).

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