DE19758557A1 - Low pressure atomizer with several adjacent two-substance nozzles, especially for fluid and gaseous mediums - Google Patents

Abstract

The supply pipe (22) for a fluid medium and at least two inlet channels (25) for a gaseous medium open into the torsion chamber (23). The inlet channels are arranged-off-set relative to each other on the circumference of the torsion chamber. The inlet channels open tangentially into the chamber and are preferably evenly spaced from each other. An Independent claim describes a low pressure atomizer device used with the above nozzle.

Description

The invention relates to a low-pressure atomization device with a plurality of adjacent ones Two-substance nozzles.

Two-component nozzles are known under the term nozzles with an inner mixture, for example from the DE specialist journal Chemie-Ingenieur-Technik 62 (1990) 12, pages 983-994. The nozzles shown in Fig. 9 either have a very complicated structure or lead to inadequate mixing and atomization of the liquid. Liquid channels protruding into the swirl chambers are difficult to manufacture, particularly with small dimensions. Nozzle openings, which are also overflowed by gas on the outside of the trailing edge, require very precisely aligned gas channels and correspondingly complex production. Due to the relatively large flow area for the gas, they also cause a higher gas consumption and thus a lower efficiency.

The present invention has for its object to provide a low pressure Atomizer with multiple two-fluid nozzles to create the simpler Manufacturability enables a very good atomization of the liquid medium.

This object is achieved by the features of patent claim 1. Beneficial Refinements can be found in the subclaims.

In the low-pressure atomization device according to the invention with several neighboring ones Two-substance nozzles each open at least two offset on the circumference of a swirl chamber entry channels arranged in relation to one another into these. This creates an even swirl generates a very fine, even distribution of the supply line inflowing liquid medium causes. The use of at least two Entry channels cause such a uniform flow of liquid and gas in the Swirl chamber that surprisingly on a second to the outlet opening of the nozzle concentric and slit-shaped gas channel (Chem.-Ing.-Tech. 62 (1990) 12, pp. 983-994) can be dispensed with. The low pressure atomization device becomes axial Direction formed by several closely connected components. The Nozzle outlet and at least the tapering part of the swirl chamber in a lower one Plate, furthermore the inlet channels for the gaseous medium at least partially in one middle plate and the supply line at least with its inlet side on one upper plate adjacent or formed in this. Due to the multi-part training both the outlet geometry of the nozzle and the swirl chamber with the one in it incoming lines and channels in the simplest way without special tools producible.

The plurality of components forming the nozzle are advantageously form-fitting in the axial direction or non-positively, the latter connected to each other for example by screws. For the Centering and / or sealing between the individual components, it is advantageous if at least the middle plate over protruding frets with the neighboring upper plate and / or the adjacent lower plate is connected in a radially sealing manner.  

In the joined plates are preferably in the area of their parting surfaces Longitudinal channels to supply the inlet channels and / or longitudinal lines to supply the Feed lines of several two-substance nozzles are formed. Through this low pressure Atomizing device that modular any number of neighboring Two-substance nozzles with common supply lines or channels is one easy adaptation to different performance ranges of such Atomizing device possible. The mass flow rate of liquid and gaseous Medium can in this way by a flat or row-shaped composition several dual-substance nozzles can be controlled as required.

In such a low-pressure atomization device, the longitudinal channels are preferably annular groove-shaped with the inlet channels surrounding the swirl chamber Connection channels in connection.

In the case of a two-component nozzle which is used in a low-pressure Atomization device with several such two-substance nozzles is used, it is particularly advantageous if the inlet channels are slit-shaped on the lower plate facing underside of the middle plate are formed, the upper cover surface of the slot-shaped inlet channels for the entry into the swirl chamber sloping downwards. Such channels can be produced and assigned very easily by means of a disk milling cutter have the advantage that the gaseous medium supplied by the obliquely tapering Channel is accelerated and in addition to the tangential component also an axial Component is imprinted.

Advantageously, the inlet channels are essentially tangential to the swirl chamber arranged at the mouth. This results in a particularly good distribution of the liquid Medium along the walls of the swirl chamber. Those are particularly advantageous Entry channels evenly spaced from each other.

The feed line for the liquid medium is advantageously axially in a central arrangement in the Swirl chamber arranged in the mouth. With the simultaneous tangential introduction of the gaseous medium results in a vertical meeting of the two  Media directly at the point of exit of the liquid in the swirl chamber cover, which in Connection with the resulting cyclone-like flow immediately a uniform Distribution of the liquid as a film on the walls of the swirl chamber and on the Outlet cone enables. A pre-division of the liquid, which leads to a loss of momentum of the This avoids gas and coarser drops. A central feed pipe (Chem.-Ing.-Tech., 62 (1990) 12, pp. 983-994), however, leads to one less even distribution of the liquid in the swirl chamber and to a stronger and unfavorable braking of the swirl component of the gas. This can a. on the Pre-separation of the liquid can be returned, which is at the end of the swirl chamber protruding central tube in a mostly irregular manner.

In one embodiment, the swirl chamber is essentially cylindrical, a tapering part adjoining the nozzle outlet in the direction of flow. By this design becomes the cyclone-like vortex in the tapered part Nozzle outlet accelerated. The tapered part can advantageously be a hollow cone be formed, the lateral surfaces of which enclose a cone angle (α) of between 45 ° and 90 °, preferably between 50 ° and 70 °.

According to an alternative embodiment it is provided that the swirl chamber essentially is hemispherical and in the flow direction to the nozzle outlet at the concave, hemispherical part adjoins a convex tapered part. At this in terms of production compared to the swirl chamber with cylindrical and hollow cone Designing a more complex variant can result in particularly uniform acceleration and dilution of the liquid film to the nozzle outlet.

Favorable geometric conditions of the nozzle exist when the ratio of the Diameter of the swirl chamber to the diameter in the area of the nozzle outlet about 2-6, is preferably about 3 to 4.

Furthermore, advantageous loading conditions arise on the nozzle according to the invention then when the ratio of the mass of liquid to mass of gas is about 0.1 to 4.0 is preferably 0.5 to 2.0.  

Favorable flow conditions of the nozzle with an advantageous swirl and Atomization of the liquid medium results in particular from an area ratio the sum of the inflow areas, d. H. the cross sections of the inlet channels of the gaseous Medium, to the nozzle exit surface, which is about 0.5 to 3, particularly preferably 1.0 to 2.0 is. There are advantageous conditions on the two-component nozzle according to the invention continue if the nozzle pressure number, which is defined by the product of the Nozzle diameter and the pressure difference as the nozzle pressure divided by the Surface tension of the liquid to be atomized approximately between 300 and 4000, is preferably between about 400 and 2000.

The low pressure atomization device is particularly suitable for liquid fuels in burners of heating devices.

Exemplary embodiments of the invention are described below with reference to the drawing. It shows:

Fig. 1 shows a longitudinal section through a two-fluid nozzle preferably usable,

Fig. 2 is a cross section at the level of the line II-II in Fig. 1,

Fig. 3 is a partial longitudinal section through a low pressure sputtering device having a plurality of two-fluid nozzles in a first embodiment;

Fig. 4 shows a cross section through the device of FIG. 3 in height of the upper part of the swirl chambers,

Fig. 5 shows another embodiment of a low pressure atomization device and

Fig. 6 shows a cross section through the device of FIG. 5 at the section line VI-VI.

The two-substance nozzle 20 shown in FIG. 1, which can advantageously be used for a low-pressure atomization device according to the invention, is composed of several plates arranged axially one above the other. A supply line 22 for a liquid medium is arranged in an upper plate 28 . The feed line 22 runs in a central axial position. It opens with its lower end at the interface to a central plate 27 in a swirl chamber 23 formed there. The swirl chamber 23 has, in addition to an upper cylindrical part with a diameter D _K, a tapering part 33 which adjoins it at the bottom and is designed as a hollow cone in a lower plate 26 . The hollow cone has a cone angle α which is between 45 ° and 90 °, preferably between 50 ° and 70 °. The lateral surface of the hollow cone merges into a rounded contour in the area of a nozzle outlet 31 . The nozzle outlet 31 has a diameter D. The ratio of the diameter of the swirl chamber D _K to the diameter D of the nozzle outlet 31 is approximately 2 to 5, preferably approximately 3 to 4.

In the cylindrical part of the swirl chamber 23 open tangentially two uniformly on the periphery offset to one another entry passages 25 a. The inlet channels 25 have a diameter D ₂₅ , from which the sum of the inflow areas A _{E of} the gaseous medium can be calculated as the sum of the cross-sectional areas of all inlet channels 25 . The ratio of this sum A _E to the cross section of the nozzle outlet A _D is approximately 1.0 to 3.0, preferably 1.5 to 2.0. The tangential opening of the inlet channels 25 results in a cyclonic vortex in the cylindrical part of the swirl chamber 23 , through which the liquid entering perpendicularly thereto via the feed line 22 is entrained in strong swirling and accelerated along the conical part 33 and finely distributed as a film and over the tear-off edge is atomized very finely in the nozzle outlet 31 . The number of two inlet channels 25 shown in the exemplary embodiment represents the minimum for a good swirling of the liquid medium. If necessary, several inlet channels for the gaseous medium can also be provided. These are always preferably evenly spaced from one another.

For a good centering and a tight connection of the plates 26 , 27 and 28 , it is advantageous if at least on the middle plate 27 frets 37 and 38 are provided, which for engaging in or encompassing correspondingly complementary frets on the upper plate 28 and serve on the lower plate 26 .

In the exemplary embodiments according to FIGS. 3-6, several adjacent two-substance nozzles are combined to form a low-pressure atomization device. The construction explained in connection with FIGS. 1 and 2 facilitates their combination in such a common device, the supply channels for the gaseous medium and the supply lines for the liquid medium being supplied from common supply channels or lines, which can be supplied directly are formed in the device. The low-pressure atomization device shown in FIG. 3 is in turn composed of a lower plate 6 , a middle plate 7 and an upper plate 8 . On the lower side of the upper plate 8 , ie on the separating surface from the middle plate 7 , longitudinal longitudinal lines 1 are provided, in which the liquid medium reaches supply lines 2 of different adjacent two-substance nozzles. The feed lines 2 are formed in a central axial arrangement for each nozzle in the middle plate 7 . Furthermore, the middle plate 7 forms on its underside, ie on the separating surface from the lower plate 6 , an upper and lateral boundary for longitudinal channels 4 , in which the gaseous medium is led to several two-substance nozzles.

The swirl chambers 3 of the two-substance nozzles are formed in the lower plate 5 . They are in turn composed of an upper, cylindrical part in FIG. 3 and a tapering part 13 adjoining it downwards, which can be either conical or with a convex curvature. In the swirl chamber, two inlet channels 5 open tangentially in turn, which at a distance surrounds a the wall of the swirl chamber annular-groove 3 connecting channel 10 with the longitudinal channels 4 are connected. The liquid medium supplied through the longitudinal lines 1 and the feed lines 2 in turn flows axially into the swirl chamber 3 and is swirled there by the gaseous medium supplied via the longitudinal channels 4 , the connecting channels 10 and the inlet channels 5 and atomized at a nozzle outlet 11 .

As can be seen from Fig. 4, the arrangement of several two-substance nozzles is such that three adjacent two-substance nozzles form an equilateral triangle. The longitudinal channels 4 for the gaseous medium and the longitudinal lines 1 for the liquid medium run offset from one another in different planes. Due to the formation of the channels or lines in the different plates, the production is again very simple. The plates 6 , 7 and 8 are non-positively clamped together in the axial direction. For this purpose, in the exemplary embodiment, a plurality of screws 9 are provided which are equally spaced from one another. Alternatively, the plates 6 , 7 and 8 can also be connected by an adhesive, soldering, welding or sintering technique.

According to a variant shown in the lower middle part of FIG. 4, the gaseous medium can be supplied to the inlet channels 5 starting from the longitudinal channels 4 instead of via the annular groove-shaped connecting channels 10 and also via blind hole-like connecting channels 10 A. The distance between the individual nozzle outlets 11 of the various two-substance nozzles should be at least ten times their diameter, so that the spray jets do not penetrate each other too strongly and this leads to an undesired reunification of already finely atomized droplets.

In the embodiment shown in FIGS. 5 and 6, the longitudinal channels 4 are sunk into the middle plate 7 from the underside. The inlet channels 5 are also milled into the underside of the middle plate 7 as tangential slots 5 and open with their upper cover surface which runs obliquely downwards in the left part of FIG. 5 at the level of the feed lines 2 into the upper part of the swirl chamber 3 A. The swirl chamber 3 A itself is again completely formed in the lower plate 6 in the left part of FIG. 5. It has an upper part which is essentially hemispherical and merges into a lower tapering part 13 A, which has a convex wall. The transition from the concave to the convex wall is relatively easy to produce, since in this example no entry channels 5 are formed in the lower plate 6 . These inlet channels 5 are formed exclusively in the webs 12 , which separate the longitudinal channels 4 from the supply lines 2 . In this example, the upper plate 8 is designed as a smooth cover plate, since the longitudinal channels 1 for the liquid medium are also formed in the middle plate 7 from above.

In an alternative embodiment in the right part of FIG. 5, the swirl chamber 3 A also extends into the middle plate 7 . In this case, the inlet channels 5 A are formed as straight slots tangentially opening into the swirl chamber (in the upper part) in the underside of the plate 7 . The thinner lower plate 6 is thus not weakened in the exemplary embodiment according to FIG. 5 as in FIGS. 3 and 4 by additional inlet channels.

Through the illustrated combination of several two-substance nozzles into one Low pressure atomizer is a modular, economical manufacture of Atomization devices also guaranteed for larger mass throughputs. Such Low pressure atomizing devices can be used advantageously for atomizing liquid Use fuels for burners of any performance class. Because of the relative low pressure levels, the energy consumed is comparatively low. Two-substance nozzle or low-pressure atomization devices according to the invention can be also for other applications, such as evaporative cooling Conditioning of process gases or for the production of fine powders by solidification of Use atomized drops to advantage. A particularly interesting application results even with micronization of the nozzle diameter to a diameter of less than 0.5 mm using the league technique (etching process). That way Manufacture large nozzle arrays very cheaply from ceramic materials.

In one exemplary embodiment for a burner of a vehicle auxiliary heater, which was operated with diesel fuel of minus 20 ° C., with a mass flow of the fuel of M _F = 0.5 kg / H, an air pressure of Δp = 0.07 resulted bar, a nozzle diameter D = 2 mm, a swirl chamber diameter D _K = 8 mm, a cone angle α = 60 °, a gas inlet area A _E = 6.3 mm ² (which results from two inlet bores each with a diameter of 2 mm), a gas throughput of M _G = 0.85 kg / H, the average droplet size achieved (Sauter diameter) being d = 80 μm.

In a further exemplary embodiment, 8 kg / h of water are atomized in an evaporative cooler with 100 nozzles in a nozzle array. The nozzle diameter is D = 0.5 mm, the swirl chamber diameter D _K = 2 mm. The gas entry area for each nozzle is 0.3 mm ² . Even at a comparatively low gas pressure of Δp = 0.6 bar, an average droplet size (Sauter diameter) of approx. D = 20 µm can be expected according to the similarity theory.

The invention is a simple and insensitive design of two-component nozzles in Regarding compliance with manufacturing tolerances possible. The manufacture of a Low pressure atomization device is considerably cheaper. It will be a free one Liquid suction possible due to negative pressure in the liquid channel. Through the Layered composition of several processed, possibly etched plates there is an application possibility also in the area of high throughputs for small ones Drop sizes. A nozzle plate then contains a plurality of nozzles connected in parallel in a single low pressure atomizer.

By using an injector, a higher pressure can be achieved at the nozzle, with which smaller droplet dimensions, higher operating temperatures and more favorable viscosity values can be achieved at low ambient temperatures.  

Reference list

1

Longitudinal line

2nd

Supply line

3rd

,

3rd

A swirl chamber

4th

Longitudinal channel (for gas)

5

Entry channel

6

(lower plate

7

(middle) plate

8th

(top) plate

9

Screws

10th

Connecting channel (ring groove)

10th

A connecting channel (blind hole)

11

Nozzle outlet

12th

web

13

,

13

A (tapered) part

20th

Dual-substance nozzle

22

Supply line (for liquid medium)

23

Swirl chamber

25th

Entry channel

26

(lower plate

27

(middle) plate

28

(top) plate

31

Nozzle outlet

33

(tapered) part

37

Federation

38

Federation
D diameter of the nozzle (at

11

respectively.

13

)
D _K

Swirl chamber diameter

Claims (18)

1. Low-pressure atomization device with a plurality of adjacent two-substance nozzles, each of which has a swirl chamber ( 3 , 3 A), into the at least one feed line ( 2 , 22 ) for a liquid medium and at least one inlet channel ( 5 , 25 ) for a gaseous medium flows out and which are formed in the axial direction by a plurality of closely connected components (plates 6 , 7 , 8 or 26 , 27 , 28 ), wherein in the joined plates ( 6 , 7 , 8 ) longitudinal channels ( 4 ) for supplying the inlet channels ( 5 ) and / or longitudinal lines ( 1 ) for supplying the feed rates ( 2 ) of a plurality of two-component nozzles. 2. Low-pressure atomization device according to claim 1, characterized in that the longitudinal channels ( 4 ) via the swirl chamber ( 3 ) surrounding annular groove-shaped connecting channels ( 10 ) are in communication with the inlet channels ( 5 ). 3. Two-fluid nozzle ( 20 ) for use in a low-pressure atomizing device according to claim 1, characterized in that at least two on the circumference of the swirl chamber ( 3 , 3 A, 23 ) offset from each other inlet channels ( 5 , 25 ) are provided. 4. Two-fluid nozzle for use in a low-pressure atomization device according to claim 3, characterized in that the inlet channels ( 5 , 25 ) open substantially tangentially into the swirl chamber ( 3 , 3 A, 23 ). 5. Two-component nozzle according to one of claims 3 or 4, characterized in that the inlet channels ( 5 , 25 ) are evenly spaced apart. 6. Two-component nozzle according to one of claims 3 to 5, characterized in that the feed line ( 2 , 22 ) opens axially in a central arrangement in the swirl chamber ( 3 , 23 ). 7. Two-component nozzle according to one of claims 3 to 6, characterized in that the swirl chamber ( 3 , 23 ) is essentially formed by a cylindrical part, on which in the direction of flow to the nozzle outlet ( 11 , 31 ) a tapering part ( 13 , 13 A, 33 ) connects. 8. Two-component nozzle according to claim 7, characterized in that the tapering part ( 13 , 33 ) is designed as a hollow cone, the lateral surfaces of which enclose a cone angle (α) which is between 45 ° and 90 °, preferably between 50 ° and 70 ° . 9. Two-component nozzle according to one of claims 3 to 7, characterized in that the swirl chamber ( 3 A) is substantially hemispherical and in the direction of flow to the nozzle outlet ( 11 ) on the concave, hemispherical part a convexly tapering part ( 13 A) connects. 10. Two-component nozzle according to one of claims 3 to 9, characterized in that the ratio of the diameter (D _K ) of the swirl chamber ( 3 , 3 A, 23 ) to the diameter (D) in the region of the nozzle outlet ( 11 , 31 ) is approximately 2 < D _K / D <6, preferably 3 <D _K / D <4. 11. Two-component nozzle according to one of claims 3 to 10, characterized in that the ratio of the loading with mass of liquid (M _F ) to mass of gas (M _G ) is approximately 0.1 <M _F / M _G <4.0, is preferably 0.5 <M _F / M _G <2.0. 12. Two-component nozzle according to one of claims 3 to 11, characterized in that the area ratio of the sum of the inflow surfaces (A _E ) of the gaseous medium to the nozzle discharge surface (A _D ) is approximately 1.0 <A _E / A _D <3.0, preferably 1.5 <A _E / A _D <2.0. 13. Two-component nozzle according to one of claims 3 to 12, characterized in that the Nozzle pressure figure, defined by the nozzle diameter (D), the pressure difference as Nozzle pre-pressure (Δp) and the surface tension (σ) of the atomizer  Liquid, about 300 <Δp × D / σ <4000, preferably about 400 <Δp × D / σ <2000 is. 14. Two-component nozzle according to one of claims 3 to 13, characterized in that the nozzle outlet ( 11 ) and at least the tapering part ( 13 , 13 A, 33 ) in a lower plate ( 6 , 26 ) that the inlet channels ( 5 , 25 ) for the gaseous medium at least partially in a central plate ( 7 , 27 ) and that the supply line ( 2 , 22 ) at least with its inlet side adjoins an upper plate ( 8 , 28 ) or is formed therein. 15. Two-component nozzle according to one of claims 1 to 14, characterized in that the components are positively or non-positively connected to one another in the axial direction (for example by screws 9 ). 16. Two-component nozzle according to one of claims 1 to 15, characterized in that the central plate ( 7 , 27 ) via projecting collars ( 37 or 38 ) with the adjacent upper plate ( 8 , 38 ) and / or the adjacent lower plate ( 6 , 36 ) is connected in a radially sealing manner. 17. Two-component nozzle according to one of claims 3 to 16, characterized in that the inlet channels ( 5 ) are slot-shaped on the underside of the middle plate ( 7 ) facing the lower plate ( 6 ), the upper cover surface of the slot-shaped inlet channels ( 5 ) sloping downwards to enter the swirl chamber ( 3 ). 18. Two-component nozzle according to one of claims 3 to 17, characterized in that it is used as a low pressure atomizer for liquid fuels.