EP0769655B1 - Air-blast spray nozzle - Google Patents

Description

Technical field

The invention relates to the field of combustion technology. It relates to an atomizing nozzle for atomizing liquid fuel in a burner, which works on the airblast principle works, both for the operation of the burner with liquid as well as gaseous fuels and especially in low-pollution premix burners of the double-cone design can be used. Such a nozzle is e.g. known from EP 0 660 038 A2.

State of the art

The fuel must be used for low-pollutant premix combustion before combustion as homogeneous as possible with the combustion air be mixed. If liquid fuel is used, so this must be atomized beforehand. The liquid Fuel jet split into individual droplets so that the fuel has the largest possible evaporation surface receives.

For atomizing liquid fuels in combustion chambers airblast atomizers are also used Application (see A. H. Lefebvre, Airblast Atomization, Prog. Energy Combust. Sci. Vol. 6, pp. 233-261, 1980), which in particular are suitable for the operation of gas turbines. This are designed so that the relatively slow moving liquid fuel through a high speed air flow is atomized. The fuel has none Own pulse. The liquid to be atomized is, for example as a thin film with an approximately constant thickness on an atomizer edge applied. This atomizer edge is from an air flow on both sides, d. H. of an exterior and of an internal air flow, with the atomization of the Liquid fuel then on the atomizer lip in the shear field of the two air flows takes place (prefilming atomization).

As is known, the liquid fuel is either via central pressure atomizers or via so-called film layers, which is integrated in this component in the lead of the atomizer edge are and therefore require a relatively thick component, applied.

To direct the air towards the atomizer edge, the internal airflow either swirls and / or over one Central body directed outwards.

The disadvantage of this known prior art is that it is relative large component diameter or the high pressure drop in the nozzle due to the narrow cross section.

Generally, by twisting the internal air flow the nozzle diameter is relatively large. To remedy this hence the airblast atomizer with a displacement body executed. The disadvantage of this displacement body is in causing increased susceptibility to coke - and gum formation in the wake. Because of the proximity to the flame in addition, the cooling of this part is usually difficult problem to be solved.

Presentation of the invention

The invention tries to avoid all these disadvantages. you the task is based on an airblast nozzle for atomization to develop liquid fuel that is also suitable for the Gas operation can be used and is characterized by small dimensions and is therefore, for example, well suited for the Use in a premix burner of the double cone type, whereby the nozzle due to reduced susceptibility to coking and awards for gum formation. Furthermore, in the Nozzle only a slight pressure drop arise. Finally it is the object of the invention to propose a mechanism with which it succeeds in atomizing the air during gas operation throttle and when operating with liquid fuel meter the required atomizing air.

According to the invention, this is according to an airblast nozzle Preamble of claim 1 achieved by that the atomizer edges are angled along their entire length in the direction of the nozzle axis.

The advantages of the invention are the compact design the airblast nozzle and its minimum diameter so that especially in a double-cone type premix burner are good to use. Another advantage comes from that no more components are arranged at the nozzle outlet that tend to build up or overheat. Furthermore there is only a small pressure loss in the nozzle and the design pressure drop is at the atomizer lip.

It is particularly convenient if the liquid fuel pipe is axially displaceable, while the outer nozzle part of the burner and is thus firmly fixed, the Sliding point between the inner supports on the liquid fuel pipe and the partition between the inner and the outer air duct is provided. About moving the Oil film sprayer is the thermal expansion of the lance tube collected. The position of the atomizer edge relative to the Brenner therefore remains unchanged. Another advantage is saving the problematic seal between the Pilot gas line and the atomizer, because here the outer Atomizer part is part of the burner. Finally there is another advantage is that the sensitive atomizer part when installing the fuel lance in the burner can remain and is not damaged.

As an embodiment, it is also possible to in the atomizer leave whole and slide outside.

Finally, the fuel is advantageously available on the market Pressure atomizers, in particular hollow cone atomizers, applied. To apply the fuel are also simple Bores that are radial or oblique at the closed end of the Fuel line are attached, suitable. Here it is from Advantage if additionally arranged in the atomizer edge Weir the fuel film is evened out.

It is also advantageous if the inner and / or outer Support elements are designed as swirl blades. Through the Swirling the air results in better atomization. The twisting of the inner air flow serves one better flow around the atomizing lip, while the outer Swirl affects the spray angle α. Also the fuel application can be twisted (radial or oblique against the Nozzle axis).

Finally, it is a method for operating the inventive airblast nozzle, when operating with gaseous Fuel the inflow of air into the burner interior is at least partially throttled, advantageous that the throttling is due to the different thermal expansion of the liquid fuel pipe in gas or oil operation. This throttling mechanism is quite easy to implement.

Brief description of the drawing

In the drawing are several embodiments of the invention shown.

Fig. 1

eine schematische Darstellung der Anordnung eines mit einer airblast-Düse ausgestatteten Doppelkegelbrenners;

Fig. 2

einen Teillängsschnitt der airblast-Düse bei Verwendung eines konventionellen Öldruckzerstäubers;

Fig. 3

einen Teillängsschnitt der airblast-Düse, wobei eine Flüssigbrennstoffleitung mit zur Düsenachse am geschlossenen Ende schräg angeordneten Bohrungen verwendet wird;

Fig. 4

einen Teillängsschnitt der airblast-Düse mit als Drallschaufeln ausgebildeten Stützelementen und einem Wehr;

Fig. 5

einen Teillängsschnitt der airblast-Düse mit verdrallter Flüssigbrennstoffaufbringung;

Fig. 6

einen Teilquerschnitt entlang der Linie VI-VI in Fig. 4;

Fig. 7

einen Teillängsschnitt des Brennerteiles und der Brennstoffzuführung, wobei im oberen Teilbild der Gasbetrieb und im unteren Teilbild der Ölbetrieb veranschaulicht ist.

Show it:

Fig. 1

is a schematic representation of the arrangement of a double-cone burner equipped with an airblast nozzle;

Fig. 2

a partial longitudinal section of the airblast nozzle when using a conventional oil pressure atomizer;

Fig. 3

a partial longitudinal section of the airblast nozzle, wherein a liquid fuel line is used with bores arranged obliquely to the nozzle axis at the closed end;

Fig. 4

a partial longitudinal section of the airblast nozzle with support elements designed as swirl blades and a weir;

Fig. 5

a partial longitudinal section of the airblast nozzle with swirled liquid fuel application;

Fig. 6

a partial cross section along the line VI-VI in Fig. 4;

Fig. 7

a partial longitudinal section of the burner part and the fuel supply, the gas operation in the upper part and the oil operation in the lower part is illustrated.

It is only essential for understanding the invention Elements shown. The flow direction of the work equipment is marked with arrows.

Way of carrying out the invention

The invention is described below using exemplary embodiments and Figures 1 to 7 explained in more detail.

Fig. 1 shows a schematic representation of the arrangement a premix burner equipped with an airblast nozzle the double cone design.

An airblast nozzle is located in the upstream end of the burner 1 2 arranged. It is over one with the double cone burner 1 connected fuel lance 3 with liquid fuel 4 and compressed air 5, which is used to atomize the fuel 4 is used, supplied. The fuel lance also delivers 3 the gaseous fuel 6 for the double cone burner 1 while removing its main burner air 7 from the Space within the burner hood 8 receives. The air 5 for the airblast nozzle 2 can also be located outside the burner hood 8 located plenum (not shown) supplied become. In addition, in this embodiment, greasing the combustion gases near the axis of the double-cone burner 1 via the fuel lance 3 additional gaseous fuel (Pilot gas 9) injected into burner 1. downstream Burner 1 opens into combustion chamber 10.

2 shows the airblast nozzle in an enlarged partial longitudinal section 2. It has one arranged around the nozzle axis 11 Fuel pipe 12 for the liquid fuel 4 on and each an inner 13 arranged concentrically thereto and one outer air duct 14. The two air channels 13, 14 are upstream with an air supply line 15 in which the Atomizing air 5 is led to the nozzle, connected and open on the atomizing cross section 16 in the burner interior 17. Die Channels 13, 14 are through an intermediate wall 18, according to the invention at its downstream end in the direction of the nozzle axis 11 is angled and there the atomizer edge 19 the atomizer lip 20 forms, separated from each other, so that the atomizing air 5 into an outer 5a and an inner Airflow 5b is split. With the help of preferably in evenly spaced inner circumferential and outer support elements 21, the partition 18 is inclusive the atomizer edge 19 between the fuel pipe 12 and outer nozzle body 23 held. The inner support elements 21 are between the fuel pipe 12 and the Partition 18 arranged while the outer support elements 21 between the intermediate wall 18 and the nozzle outer body 23 are arranged. In the present embodiment A pilot gas channel 22 is provided in the burner 1, which pilot gas 9 provides the greasing of the gaseous Fuel 6 is used in the interior of the burner, thereby increasing the stability range the burner is expanded. The pilot gas channel 22 is shown in FIG. 2 by the outer nozzle body 23 and by the Wall of the burner 1 limited. 2 is not shown the connection of the nozzle 2 with the burner 1 and the feed of the pilot gas channel 22. The latter can for example by an arranged in the burner wall, not shown here Feed hole for the pilot gas can be realized. The nozzle 2 can e.g. about a not shown Cover that at the upstream end of the pilot gas channel 22nd on the outer nozzle body 23 and on the wall of the burner 1 over the entire circumference is welded on and the pilot gas channel 22 completes, be connected. Of course, in others Embodiments also on the arrangement of a pilot gas channel to be dispensed with.

The liquid fuel 4, preferably oil, is over a exchangeable, commercially available pressure atomizers 24 as thinner Film applied to the atomizer edge 19. Are optimal Hollow cone atomizer, but it can also be a full cone atomizer be used with a well atomized fuel core. The atomizer edges 19 are narrowed in accordance with the invention in order to in the atomizing cross section 16 or on the atomizing lip 20 to get a maximum air speed. The one in the outside Air duct 14 brought out external air flow 5a also via a constriction at the atomizer edge 19 the atomizer lip 20 brought up where the fuel film atomized finely by the shear forces of the two air streams 5a, 5b becomes. The high air speed has a positive effect for improved atomization quality.

The spray angle α can by dividing the two Air mass flows 5a, 5b and through the geometry of the outlet cross section to be influenced.

In the embodiment shown in Fig. 2 are in upper part of the figure, the inner support members 21 are not tight connected to the intermediate wall 18 so that at this point a sliding point 28 is present. This enables a shift of the liquid fuel tube 12 including the Oil pressure atomizer 24, so that the thermal expansion the fuel lance 3 can be caught and the position of the atomizer edge 19 relative to the double-cone burner 1 not changed, which is a big advantage. This Arrangement only requires a slightly longer atomizer sleeve (= Partition 18). This version also saves additionally a problematic seal between the pilot gas duct 22 and the atomizer in burner 1, since the outer Atomizer part would be part of the burner 1. Another The advantage is that the sensitive atomizer part when installing the fuel lance 3 in the double-cone burner 1 remains and is not damaged.

As a further embodiment, the lower part of Fig. 2 illustrates, it is also possible to use the atomizer to leave whole, i.e. both the inner and the outer support elements 21 are fixed to the intermediate wall 18 and the liquid fuel tube 12 and the nozzle outer body 23 connected. Then the nozzle 2 as a whole is only from the outside movable (sliding point 29).

Fig. 3 shows an embodiment in which the liquid fuel 4 via simple holes 25 on the atomizer edge 19 is applied. These are radial or oblique on closed end of the liquid fuel line 12 is arranged. In order to even out the fuel film and thereby Atomization quality can be improved in the Atomizing edge 19 weirs 26 may be arranged.

Another embodiment variant is shown in FIG. 4. In contrast to FIG. 3, the support elements 21 are as Swirl blades 27 executed. It is possible to only use the to arrange inner support elements 21 as swirl blades, so that only the inner air flow 5b is swirled for a better one To achieve flow around the atomizer lip 20. Will only the outer air flow 5a swirls, so the spray angle α are influenced. Of course, 4, both air flows 5a, 5b swirl by using both the inner and outer support elements 21 are designed as swirl generators.

Since the gas operation of the double cone burner 1 as a result of the airblast nozzle 2 flowing atomizing air 5 is disturbed, 7 becomes a mechanism for solving this problem proposed the different thermal expansion of the Fuel line 12 is used in oil and gas operation. The upper part of FIG. 7 relates to gas operation, the lower part, however, on the oil operation. 7 is the airblast nozzle 2 at the downstream end of the oil line 12 not shown. In gas operation, the atomizing air 5 throttled because the oil line 12 through the from the compressor coming air is heated and accordingly by the Thermal expansion of the oil line at the inlet area of the atomizing air 5 reduced or completely closed in the burner section becomes. In contrast to this, when operating oil or adding water the required atomizing air 5 due to the lower Thermal expansion of the colder oil line 12 under these operating conditions measured (see open entrance area the air 5 in the lower part of Fig. 7). requirement this is because the liquid fuel line 12 firmly on Housing is attached and the burner 1 firmly on the in Fig. 7 combustion chamber 10, not shown, is arranged.

Of course, 5 for throttling the atomizing air the airblast nozzle according to the invention in gas operation also others, already known throttle mechanisms, such as the throttling of the air 5 by displacement using pilot gas 9 applicable.

• kompakte Bauweise mit minimalem Durchmesser
• geringer Druckverlust in der Düse
• Auslegungsdruckabfall an der Zerstäuberlippe
• keine Bauteile am Düsenaustritt, die zu Ablagerung bzw. Überhitzung neigen
• enger Sprühwinkel α
• einfache Kalibrierbarkeit und Auswechselbarkeit der kritischen Ölquerschnitte.

In summary, it can be stated that the airblast nozzle according to the invention is characterized by the following properties:

• compact design with minimal diameter
• low pressure loss in the nozzle
• Design pressure drop at the atomizer lip
• no components at the nozzle outlet that tend to deposit or overheat
• narrow spray angle α
• easy calibration and exchangeability of critical oil cross sections.

LIST OF REFERENCE NUMBERS

1

burner

2

airblast nozzle

3

fuel lance

4

liquid fuel

5

Air for the airblast nozzle

5a

external airflow

5b

internal airflow

6

gaseous fuel

7

Main burner air

8th

burner hood

9

pilot gas

10

combustion chamber

11

nozzle axis

12

fuel pipe

13

outer air duct

14

inner air duct

15

Air supply line

16

Zerstäubungsquerschnitt

17

Burner interior

18

partition

19

atomizer

20

atomizer

21

support elements

22

Pilot gas channel

23

Nozzle outer body

24

Öldruckzerstäuber

25

drilling

26

weir

27

swirl generator

28.29

sliding point

α

spray angle

Claims (10)

1. Airblast atomizer nozzle (2) for the operation of a burner (1) operated with liquid and gaseous fuels (4, 6), the nozzle (2) consisting essentially of a liquid fuel pipe (12) arranged centrally around the nozzle axis (11) and having at least one means, located at the end, for applying the liquid fuel (4) to an atomizer edge (19), as well as of two concentric air ducts (13, 14) fed by an air feed conduit (15), and optionally of a pilot gas duct (22) arranged concentrically thereto, the ducts (13, 14, 22) being separated from one another in each case by intermediate walls (18), as well as of a nozzle outer body (23), the air ducts (13, 14) opening into the burner interior (17) at the atomization cross section (16) of the nozzle (2), the outer air duct (13) narrowing upstream of the atomization cross section (16), and the intermediate wall (18) between the inner (14) and outer (13) air duct forming the atomizer edge (19) at the downstream end, and the intermediate wall (18) between the inner (14) and outer (13) air duct being held via inner and outer support elements (21), the inner support elements being arranged between the intermediate wall (18) and the fuel pipe (12) and the outer support elements (21) being arranged between the intermediate wall (18) and the nozzle outer body (23), characterized in that the atomizer edges (19) are angled in the direction of the nozzle axis (11) over their entire length.
2. Airblast atomizer nozzle according to Claim 1, characterized in that the liquid fuel pipe (12) is axially displaceable, whilst the nozzle outer body (23) is an integral part of the burner (1) and is thus firmly fixed.
3. Airblast atomizer nozzle according to Claim 1, characterized in that its individual components are firmly fixed and the nozzle (2) is axially displaceable as a whole only.
4. Airblast atomizer nozzle according to Claim 2, characterized in that a sliding point (28) is provided between the inner support elements (21) on the liquid fuel pipe (12) and the intermediate wall (18) between the inner (14) and the outer (13) air duct.
5. Airblast atomizer nozzle according to Claim 1, characterized in that the means for applying the liquid fuel (4) is an oil-pressure atomizer (24).
6. Airblast atomizer nozzle according to Claim 5, characterized in that the oil-pressure atomizer (24) is a hollow-cone atomizer.
7. Airblast atomizer nozzle according to Claim 5, characterized in that the oil-pressure atomizer (24) is a solid-cone atomizer.
8. Airblast atomizer nozzle according to Claim 1, characterized in that the means for applying the liquid fuel (4) are radially or obliquely arranged bores (25) at the closed end of the fuel pipe (12).
9. Airblast atomizer nozzle according to Claim 8, characterized in that weirs (26) are arranged at the atomizer edge (19).
10. Airblast atomizer nozzle according to Claim 1, characterized in that the outer and/or inner support elements (21) are designed as swirl generators (27), particularly as swirl vanes.

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