EP1781988B1 - Hybrid burner lance - Google Patents

Description

Technical area

The invention relates to a lance for a hybrid burner of a combustion chamber of a gas turbine, in particular a gas turbine for a power plant.

State of the art

With the aid of such a lance, a liquid fuel, for example a suitable oil, and a gaseous fuel, for example natural gas, can be injected alternatively or cumulatively into a hybrid burner. Such a lance for injecting pre-mixed with combustion air liquid and / or gaseous fuel in a gas turbine engine, for example, in the document US 5836163 described. This device allows operation of the gas turbine with liquid or gaseous main fuel and liquid or gaseous pilot fuel. For this purpose it has a gaseous fuel feeder, a liquid fuel feeder and a compressed combustion air feeder which service the different fuel and combustion air paths. Thus, this device comprises a central flow channel (46) for liquid fuel, a coaxially positioned duct (52) for supplying combustion air, another annular channel (54) for gaseous fuel surrounding the latter and terminating in an outlet (55). These three inner channels primarily serve pilots. In addition, this device has an annular channel (76) for liquid fuel, a secondary air channel (58), a main air channel (64) and an outer collecting channel (66), from the gaseous main fuel via spokes (68) and openings (70) introduced therein. is injected into the combustion air duct (64) and mixed with the air supplied from the compressor. The resulting mixture is fluidized in the mixing chamber (128) and then exits into the annular combustion chamber (32).
An air inlet plate (118) distributes and controls the mass flow of the combustion air supplied by the compressor.
By adjusting the air inlet plate (118) and feeding the respective fuel channels with the intended fuel different operating modes of the combustion chamber with liquid or gaseous main fuel with or without pilot support possible.

In stationary gas turbine plants, the supply of the lance with the gaseous fuel usually takes place via a pipeline, in which a gas pressure predetermined by the gas supply system prevails. In a variety of applications, such as a combustion chamber with low-pressure burner and downstream high-pressure burner, this system pressure present in the pipeline, however, is too low to be able to inject the gaseous fuel with sufficient pressure difference through the lance into the combustion chamber. Accordingly, it is common to place an additional compressor upstream of the lance to raise the gaseous fuel to the required pressure level. However, the installation of such an additional compressor increases the installation cost of the combustion chamber or the equipped gas turbine. In addition, the additional compressor for its operation requires energy, which reduces the efficiency of the power plant in a preferred application of the gas turbine in a power plant for power generation.

Presentation of the invention

The invention aims to remedy this situation. The invention, as characterized in the claims, deals with the problem of providing a lance of the type mentioned an improved embodiment, which in particular allows operation of the hybrid burner equipped with a comparatively low pressure in the gaseous fuel, but a ensures certain pressure difference to the gas path, so that the flame front can not migrate into the gas path opposite to the gas flow direction.

This problem is solved by the subject matter of the independent claim. Advantageous embodiments are the subject of the dependent claims.

The invention is based on the general idea of reducing aerodynamic improvements in the gas path of the lance whose flow resistance, thereby reducing the pressure drop occurring in the flow through the lance. As a result, it can lower the pressure required in the gaseous fuel upstream of the lance. The aim is to lower the flow resistance in the gas path of the lance as far as possible so that the remaining pressure drop already a proper operation of the burner with the system pressure prevailing in the pipeline allows. This means that it is then possible to dispense with an additional compressor upstream of the lance.

In the case of the invention, the flow resistance in the gas path of the lance is significantly reduced in particular because, in the case of a distributor section which is arranged upstream of the outer nozzles in the outer channel and which has a plurality of star-shaped, axially extending passage openings for the gaseous fuel, the passage openings are dimensioned in that these each have a larger opening width in the circumferential direction than in the radial direction. By this construction, the flow-through cross-section in the manifold section is considerably increased, which reduces its flow resistance accordingly. In this case, the invention utilizes the knowledge that a particularly serious pressure drop arises during the flow through the distributor section within the lance, so that there is a particularly great potential for the reduction of the flow resistance.

According to an advantageous embodiment, the outer channel may be limited axially in the region of the outer nozzles by an outer end wall, whereby the outer channel is axially closed. In the case of each outer nozzle, an axial recess is then formed in the outer end wall on a side remote from the distributor section. With the help of such a depression, the inner nozzles extending coaxially within the outer nozzles can flow much better, which considerably simplifies the flow of the gaseous fuel from the outer tube into the outer nozzles, in particular at its side remote from the distributor section. Accordingly, the flow resistance is significantly reduced even in the region of the transition between outer tube and outer nozzle. At the same time, in such an embodiment, the homogeneity of the flow through the outer nozzles and thus the quality of the injection of the gaseous fuel can be improved.

A further reduction of the pressure drop in the gas path of the lance can be realized in another embodiment in that with each outer nozzle, a transition from the outer channel to an outer nozzle channel formed in the interior of the respective outer nozzle is provided with an inlet zone tapering in the direction of flow. Such an inlet zone reduces the flow resistance during the deflection of the gas flow, which also reduces the total resistance of the lance.

Further important features and advantages of the lance according to the invention will become apparent from the subclaims, from the drawings and from the associated description of the figures with reference to the drawings.

Brief description of the drawings

Fig. 1

eine vereinfachte Prinzipdarstellung einer Lanze nach der Erfindung im Einbauzustand,

Fig. 2

eine perspektivische, teilweise geschnittene Ansicht auf einen Kopf der Lanze,

Fig. 3

eine teilweise geschnittene, perspektivische Ansicht auf den Lanzenkopf gemäß Fig. 2 entsprechend einer in Fig. 2 mit III gekennzeichneten anderen Blickrichtung,

Fig. 4

einen halben Längsschnitt des Lanzenkopfs in einem Düsenbereich.

Preferred embodiments of the invention are illustrated in the drawings and will be described in more detail in the following description, wherein like reference numerals refer to the same or similar or functionally identical components. Show, in each case schematically,

Fig. 1

a simplified schematic representation of a lance according to the invention in the installed state,

Fig. 2

a perspective, partially cutaway view of a head of the lance,

Fig. 3

a partially cut, perspective view of the lance head according to Fig. 2 according to one in Fig. 2 with III marked other direction,

Fig. 4

a half longitudinal section of the lance head in a nozzle area.

Corresponding Fig. 1 includes a here only partially indicated combustion chamber 1, at least one hybrid burner 2, which is equipped with a lance 3. The combustion chamber 1 is preferably a component of a gas turbine, not shown here, in particular for generating electricity within a power plant.

The hybrid burner 2 may burn both gaseous fuels, such as natural gas, and liquid fuels, such as a suitable oil. Accordingly, the lance 3 is connected on the one hand to a liquid fuel supply line 4 and on the other hand to a gas fuel supply line 5. In the liquid fuel supply line 4, a pump 6 is usually arranged in order to be able to supply the liquid fuel with the required supply pressure. In contrast, the gas fuel supply line 5 is connected substantially directly to a pipeline, not shown here, which provides the gaseous fuel at a comparatively low pipeline pressure. Due to the inventive design of the lance 3, it is possible to dispense with a compressor in the gas fuel supply line 5 upstream of the lance 3.

The burner 2 compressed air is supplied according to an arrow 7 from a compressor, not shown. The lance 3 is introduced with respect to the flow direction of the air 7 substantially radially to the burner 2 and has a projecting into the burner 2, substantially rectangular angled lance head 8. The lance head 8 is thus with respect to its longitudinal central axis 9 parallel to the main flow direction of the supplied air. 7 oriented. The lance head 8 is configured such that it injects the liquid and / or gaseous fuel radially into the burner 2 with respect to its longitudinal central axis 9, that is, with respect to the main flow direction of the air 7 prevailing in the burner 2.

The following explanations relate in particular to the lance head 8.

According to the Fig. 2 and 3 contains the lance 3 in its head 8 an inner channel 10 for liquid fuel and an outer channel 11 for gaseous fuel. The two channels 10, 11 are arranged coaxially with each other, so that the outer channel 11 surrounds the inner channel 10. Accordingly, the outer channel 11 has an annular cross section, while the inner channel 10 has a full cross section. Inner channel 10 and outer channel 11 are separated by an inner tube 16 and enclosed by a coaxially arranged outer tube 17.

For injection of the gaseous fuel, the lance 3 is equipped at its head 8 with a plurality of outer nozzles 12, which are arranged in a star shape with respect to the longitudinal central axis 9 and extend radially from the outer channel 11. The outer nozzles 12 each contain an outer nozzle channel 13 which extends radially from the outer channel 11 and communicates with this. Accordingly, the gaseous fuel can be injected into the burner 2 via the outer nozzles 12.

In a corresponding manner, the lance 3 is also equipped at its head 8 with internal nozzles 14, which are also arranged in a star shape with respect to the longitudinal central axis 9 and thereby depart radially from the inner channel 10. In each case, an inner nozzle 14 is arranged coaxially within an outer nozzle 12, wherein inner nozzles 14 and outer nozzles 12 radially outwardly each ends approximately flush. Each inner nozzle 14 includes an inner nozzle channel 15 which communicates with the inner channel 10. Accordingly, the liquid fuel can be injected into the burner 2 via the inner nozzles 15.

The coaxial arrangement of the nozzles 12, 14 results in an annular cross section for the outer nozzle channel 13, while the inner nozzle channel 15 has a full cross section.

In the outer channel 11, a distributor section 18 is arranged upstream of the outer nozzles 12, which in Fig. 2 characterized by a curly bracket. The distributor section 18 forms an annularly closed axial section of the lance 3 or of the lance head 8 and may in particular be formed in one piece on the outer tube 17. The distributor section 18 is thus arranged in the flow-through cross section of the outer channel 11. However, in order for the gaseous fuel to be able to reach the outer nozzles 12, the distributor section 18 is provided with a plurality of star-shaped passage openings 19 which extend axially through the distributor section 18. Such a distributor section 18 is required in order to avoid a damage event in which the lance head 8 z. B. has become leaky due to overheating, to ensure a certain pressure difference to the gas path, so that the flame front can not migrate into the gas path against the gas flow direction and thus not too much fuel can flow uncontrollably into the burner 2.

In order for the gaseous fuel distributor section 18 to have as low a flow resistance as possible, the passage openings 19 are each designed such that they have a larger opening width in the circumferential direction than in the radial direction. In Fig. 3 For example, the circumferential opening width oriented in the circumferential direction is marked by an arrow 20, while the radially-oriented radial opening width is indicated by an arrow 21. It can be clearly seen that the circumferential opening width 20 is more than twice as large as the radial opening width 21. In particular, the circumferential opening width 20 is approximately three to five times larger, preferably approximately four times larger than the radial opening 21. By the selected dimensioning of the through holes 19, this results in a comparatively low flow resistance, so that the occurring during the flow through the manifold section 18 pressure drop is correspondingly low. As a result, a comparatively low flow resistance also results for the lance 3.

In the preferred embodiment shown here, the passage openings 19 extend in the circumferential direction in each case along a circular arc segment, as a result of which a particularly large flow-through cross section for the respective passage openings 19 can be achieved. In principle, other cross-sectional geometries may also be used, for example elliptical cross sections.

Without limitation of generality, four through holes 19 are provided in the embodiment shown here. The individual passage openings 19 are separated from one another in the circumferential direction by webs 22. The webs 22 extend radially and axially with respect to the longitudinal central axis 9. Compared to the through holes 19, these webs 22 have only a comparatively small cross section. Preferably, the circumferential opening width 20 of the through openings 19 is at least three times greater than a wall thickness 23 of the webs 22 measured in the circumferential direction. In particular, the webs 22 are dimensioned such that the circumferential opening width 20 of the through openings 19 is approximately four to eight times greater than the wall thickness 23 Footbridges 22.

Referring to Fig. 4 is particularly clear that the outer channel 11 is axially closed by an outer end wall 24 in the region of the outer nozzle 12. Since the outer nozzles 12 and the outer nozzle channels 13th With respect to the outer channel 11 are radially oriented, it comes at a transition 25 between the outer channel 11 and outer nozzle channel 13 to a relatively strong flow deflection, which in Fig. 4 is shown by arrows. In order to reduce the pressure drop associated with the flow deflection, an axial recess 26 can be recessed in the outer end wall 24 in each outer nozzle 12 at a side facing away from the distributor section 18, according to an advantageous embodiment. This depression 26 makes it easier for the gas flow in the inner channel 11 to flow around the respective inner nozzle 14. As a result, the deflection of the gas flow at the side facing away from the distributor section 18 side with the outer nozzle 12 can be improved. This leads to an equalization of the pressure distribution within the transition 25, with the result that on the one hand reduces the flow resistance in the region of the transition 25 and on the other hand, the homogeneity of the flow distribution within the outer nozzle channel 13 is improved.

The depressions 26 can - as here in Fig. 4 shown - be provided separately for each outer nozzle 12, in which case an embodiment is preferred in which the recess 26 is configured with respect to a longitudinal central axis 27 of the nozzles 12, 14 circular arc segment-shaped. As a result, so-called "dead water areas" can be reduced and the flow resistance can be lowered. Alternatively, it is also possible in principle to provide a common depression 26 for all external nozzles 12. Such a common recess 26 then forms in the outer end wall 24 a circumferentially closed circumferential annular groove. Such an embodiment can be produced particularly easily.

Particularly favorable values for the pressure drop at the transition 25 can be achieved if the dimensioning of the recess 26 is matched to the dimension of the outer nozzle channel 13 in a special way. Cheap is For example, an embodiment in which a relative to the longitudinal central axis 27 of the outer nozzle 12 measured radial depth 28 is about twice or at least twice greater than a radial distance 29 between an unspecified inner wall of the outer nozzle 12 and an unspecified outer wall of the inner nozzle 14 arranged therein ,

Another measure for reducing the pressure loss within the lance 3 is seen in an aerodynamic optimization of the transition 25. For this purpose, the transition 25 according to Fig. 4 be equipped with an inlet zone 30, which tapers in the flow direction. As a result, the flow resistance during the transition from the outer channel 11 is reduced in the respective outer nozzle channel 13. The taper of the inlet zone 30 can be achieved by a simple chamfering. It is also possible to design the rejuvenation rounded.

Like that Fig. 2 to 4 can be removed, a divider 31 is suitably arranged in the inner channel 10 in the region of the inner nozzles 14. The divider 31 includes a core 32 that extends concentrically within the inner channel 10. At this core 32 dividing walls 33 are formed, which extend radially and axially and thereby protrude from the core 32 in a star shape, such that they touch the inner tube 16. Advantageously, the core 32 and the partition walls 33 are designed swept in the direction of flow to the longitudinal central axis 9. With the help of such a divider 31, the deflection of the liquid flow in the inner channel 10 can be improved on the inner nozzle 14.

Particularly advantageous is now in the Fig. 2 and 3 illustrated embodiment in which a distance 34 between the core 32 and the inner tube 16 is at least twice greater than a core diameter 35. In such a construction, the inner tube 16 in the region of the divider 31 is not or only slightly widened in order to ensure the most constant flow cross-section up to the inner nozzle 14 can. This has the consequence that the outer channel 16 may have a larger flow cross-section in the region of the outer nozzles 12, so that even in the outer channel 11 to the outer nozzles 12 as constant a flow cross-section can be achieved. Thus, this measure ultimately leads to a reduction of the flow resistance in the gas path of the lance. 3

The Fig. 2 and 3 In addition, another special feature can be removed, since there the core 32 projects axially from an inner end wall 36, which axially closes the inner duct 10 in the region of the inner nozzles 14. In order to improve the deflection to the inner nozzle 14, a transition 37 from the core 32 to the inner end wall 36 may now be configured kehlförmig. As a result, it is possible to build the divider 31 axially shorter. For the core 32, for example, an axial length 38 is preferred, which is about the same size as or may be smaller than an opening cross section 39 of the inner channel 10 in the region of the inner nozzle 14. This relatively short divider 31 in turn allows expansion in the outer channel 11 and leads there to a reduced flow resistance.

LIST OF REFERENCE NUMBERS

1

combustion chamber

2

hybrid burner

3

lance

4

Liquid fuel supply line

5

Gas fuel supply line

6

pump

7

air

8th

lance head

9

Longitudinal central axis of 8

10

internal channel

11

outer channel

12

outer nozzle

13

Outer nozzle channel

14

inner nozzle

15

Internal nozzle channel

16

inner tube

17

outer tube

18

manifold section

19

Through opening

20

Extensive opening width

21

Radial opening width

22

web

23

Web wall thickness

24

outer end wall

25

crossing

26

deepening

27

Longitudinal central axis of 12 and 14

28

Depth of 26

29

Distance between 12 and 14

30

inlet zone

31

divider

32

core

33

partition wall

34

Distance between 32 and 16

35

core diameter

36

inner end wall

37

throat-shaped transition

38

core length

39

Interior duct diameter

Claims (12)

1. Lance for a hybrid burner (2) of a combustor (1) of a gas turbine,

   - having a central inner passage (10) for a liquid fuel,

   - having an outer passage (11), coaxially enclosing the inner passage (10), for a gaseous fuel,

   - having a plurality of radially arranged outer nozzles (12) branching off radially from the outer passage (11),

   - having a plurality of inner nozzles (14) which branch off radially from the inner passage (10) and which each extend coaxially inside one of the outer nozzles (12),

   characterized in that a distributor section (18) is arranged upstream of the outer nozzles (12) in the outer passage (11) and has a plurality of radially arranged, coaxially extending through-openings (19) for the gaseous fuel, these through-openings (19) each having an opening width which is larger in the circumferential direction than in the radial direction.
2. Lance according to Claim 1, characterized in that the through-openings (19) each extend in the circumferential direction along a segment of an arc of a circle.
3. Lance according to Claim 1 or 2, characterized in that the through-openings (19) are defined in the circumferential direction by radially and axially extending webs (22), and the opening width (20) of the through-openings (19) in the circumferential direction is at least three or about four to eight times larger than a wall thickness (23) of the webs (22) in the circumferential direction.
4. Lance according to one of Claims 1 to 3, characterized in that the outer passage (11) is axially closed in the region of the outer nozzles (12) by an outer end wall (24), and, at each outer nozzle (12), an axial recess (26) is formed in the outer end wall (24) on a side remote from the distributor section (18).
5. Lance according to Claim 4, characterized in that a separate recess (26) is provided for each outer nozzle (12).
6. Lance according to Claim 5, characterized in that the recess (26) is designed in the shape of an arc of a circle coaxially to the outer nozzle (12).
7. Lance according to Claim 4, characterized in that a common recess (26) which extends in a closed annular shape in the circumferential direction is provided for all outer nozzles (12).
8. Lance according to one of Claims 4 to 7, characterized in that the recess (26), relative to a longitudinal centre axis (27) of the respective outer nozzle (12), has a radial depth (28) which is at least twice as large as a radial distance (29) between an inner wall of the outer nozzle (12) and an outer wall of the inner nozzle (14) arranged therein.
9. Lance according to one of Claims 1 to 8, characterized in that, at each outer nozzle (12), a transition (25) from the outer passage (11) to an outer-nozzle passage (13) formed in the interior of the respective outer nozzle (12) is provided with an inlet zone (30) narrowing in the flow direction.
10. Lance according to one of Claims 1 to 9, characterized in that a splitter (31) is arranged in the region of the inner nozzles (14) in the inner passage (10), this splitter (31) having a core (32) arranged concentrically to the inner passage (10) and radially and axially extending dividing walls (32) which project radially from said core (32) up to an inner tube (16) defining the inner passage (10) radially on the outside, and in that a distance (34) between the core (32) and the inner tube (16) is at twice as large as a core diameter (35).
11. Lance according to Claim 10, characterized in that the core (32) projects axially from an inner end wall (36) axially closing the inner passage (10) in the region of the inner nozzles (14), and in that a transition (37) from the core (32) to the inner end wall (36) is designed in the form of a fillet in longitudinal section.
12. Lance according to Claim 10 or 11, characterized in that an axial length (38) of the core (32) is approximately the same size as or is smaller than an opening cross section (39) of the inner passage (10) in the region of the inner nozzles (14).

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