Jet burner with cooling duct in the base plate

Abstract

A jet burner has a hot-gas side, which faces toward a combustion chamber during operation, and a cold-gas side, which faces away from a combustion chamber, including a base plate on which there are arranged multiple jet nozzles, wherein the base plate has at least one cooling duct, wherein the at least one cooling duct issues into a burner stage which comprises a pilot burner arranged on the base plate.

Claims

1. A jet burner comprising a hot gas side which, in operation, is oriented toward a combustion chamber and a cold gas side which is oriented away from the combustion chamber, the jet burner comprising: a base plate on which there are arranged multiple jet nozzles, wherein the base plate comprises at least one cooling duct which opens into a burner stage that comprises a pilot burner arranged on the base plate, wherein the at least one cooling duct extends over an entire surface area of the base plate, such that cooling air is adapted to be guided through the at least one cooling duct from radially outside to radially inside between a hot gas side of the base plate and a cold gas side of the base plate and such that the cooling air is adapted to flow around the multiple jet nozzles, wherein the at least one cooling duct opens only to the pilot burner, and wherein the at least one cooling duct is adapted to be fed with the cooling air via an opening on the cold gas side of the base plate.

2. The jet burner as claimed in claim 1, wherein the burner stage comprises the pilot burner arranged on the base plate and air required for operation of the pilot burner is adapted to be supplied from the at least one cooling duct.

3. The jet burner as claimed in claim 1, wherein the base plate comprises on its hot gas side a thermal barrier coating.

4. The jet burner as claimed in claim 1, wherein the at least one cooling duct is adapted to be fed with the cooling air via an opening on a circumferential rim of the base plate.

5. The jet burner as claimed in claim 1, wherein the at least one cooling duct is adapted to be fed with the cooling air via a cooling air line which is arranged in a wall surrounding the multiple jet nozzles and adjoining the base plate, and which is open toward the cold gas side of the jet burner and opens into the base plate.

6. The jet burner as claimed in claim 1, wherein the at least one cooling duct in the base plate comprises elements for increased heat transfer.

7. The jet burner as claimed in claim 6, wherein the elements comprise ribs or dimples.

8. The jet burner as claimed in claim 6, wherein the at least one cooling duct in the base plate comprises elements for flow guiding.

9. The jet burner as claimed in claim 8, wherein the elements for flow guiding comprise spoilers.

10. The jet burner as claimed in claim 1, wherein at least the base plate is a cast part.

11. The jet burner as claimed in claim 10, wherein the cast part comprises jet nozzles.

12. The jet burner as claimed in claim 1, wherein at least the base plate is a sheet metal construction.

13. The jet burner as claimed in claim 1, wherein a circumferential wall extending beyond the cold gas side of the base plate approaches a central axis of the jet burner with increasing distance from the base plate.

14. The jet burner as claimed in claim 1, wherein the multiple jet nozzles are arranged in an annular fashion and form an outer ring.

15. The jet burner as claimed in claim 14, wherein each jet nozzle comprises a circular cross-section.

16. A jet burner comprising a hot gas side which, in operation, is oriented toward a combustion chamber and a cold gas side which is oriented away from the combustion chamber, the jet burner comprising: a base plate on which there are arranged a pilot burner and multiple jet nozzles in an annular fashion about the pilot burner, wherein the base plate comprises a cooling duct, wherein the cooling duct originates at a radially outer side of the base plate and extends radially inward over an entire surface area of the base plate between a hot gas side of the base plate and a cold gas side of the base plate and is configured such that cooling air is adapted to flow around the multiple jet nozzles, and wherein an entirety of the cooling air that enters the cooling duct is delivered to the pilot burner.

17. The jet burner as claimed in claim 16, wherein a circumferential wall extending beyond the cold gas side of the base plate approaches a central axis of the jet burner with increasing distance from the base plate such that the circumferential wall forms a diffuser to slow the cooling air provided by a compressor.

18. The jet burner as claimed in claim 16, wherein the cooling duct is adapted to be fed with the cooling air via an opening on a circumferential rim of the base plate.

19. A jet burner, comprising: a base plate comprising a hot side disposed toward a combustion chamber and a cold side disposed away from the combustion chamber; a pilot burner; an annular cooling duct formed in the base plate between the hot gas and the cold side and comprising an inlet at a radially outer side of the base plate and a sole outlet only to the pilot burner; and multiple jet nozzles disposed about the pilot burner, each jet nozzle comprising a nozzle wall that penetrates the base plate and the annular cooling duct from the cold side to the hot side, thereby reducing a flow area of the annular cooling duct.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention will be explained in more detail by way of example with reference to the drawings, which are schematic and not to scale, and in which:

(2) FIG. 1 shows a jet burner according to the prior art,

(3) FIG. 2 shows a section through a jet burner perpendicular to a central axis of the burner,

(4) FIG. 3 shows a section through a further jet burner perpendicular to a central axis of the burner,

(5) FIG. 4 shows a section through a part of a jet burner according to the invention with possibilities for drawing cooling air,

(6) FIG. 5 shows a further possibility for drawing cooling air,

(7) FIG. 6 shows an embodiment of the cooling concept according to the invention, in which air flows through a cooling duct in the form of a cavity and

(8) FIG. 7 shows a section through a jet burner according to the invention, perpendicular to the central axis, with a view into the cavity.

DETAILED DESCRIPTION OF INVENTION

(9) FIG. 1 shows schematically a section through a part of a jet burner 1 in the longitudinal direction, that is to say along the central axis 2 of the burner 1 according to the prior art. The burner 1 has at least one jet nozzle 4 arranged in a nozzle carrier 3. The jet nozzle 4 comprises a jet nozzle inlet 5 and the jet nozzle outlet 6. The combustion chamber 7 adjoins the jet nozzle outlet 6. In addition, the jet nozzle 4 is arranged in the nozzle carrier 3 such that the jet nozzle inlet 5 is oriented toward the rear wall 8 of the burner 1. That side of the jet burner 1 which is oriented toward the combustion chamber 7 is termed the hot gas side 9; the side oriented away from the combustion chamber 7 is termed the cold gas side 10. A fuel nozzle 11 is arranged in the region of the jet nozzle inlet 5 of the jet nozzle 4. Fuel is injected into the jet nozzle 4 through the fuel nozzle 11. The burner 1 further comprises a radiallywith respect to the central axis 2 of the burner 1outer casing part 12 which, with the nozzle carrier 3, forms an annular duct 13. Air 14 from the compressor flows through this annular duct 13 toward the rear wall 8 of the burner 1 where it is deflected, such that it passes through the jet nozzle inlets 5 into the jet nozzles 4.

(10) What FIG. 1 does not show is that burners, in particular premix burners such as the jet burner 1 shown, can be equipped with an additional pilot burner in order to ensure stable combustion over a broad operating range, in particular under zero load and partial load. Such a pilot burner is then typically arranged on the central axis 2 of the burner.

(11) FIG. 2 shows, schematically, a section through a jet burner 1 perpendicular to a central axis 2 of the burner 1. The nozzle carrier 3 has a circular cross section. A certain number of jet nozzles 4 is arranged, in essentially annular fashion, within the nozzle carrier 3. In that context, each jet nozzle 4 has a circular cross section.

(12) FIG. 3 shows, schematically, a section through a jet burner 101, wherein the section runs perpendicular to the central axis of the burner 101. The burner 101 also has a nozzle carrier 3, which has a circular cross-section and in which there is arranged a number of inner and outer jet nozzles 4, 104. The jet nozzles 4, 104 each have a circular cross-section, wherein the cross section area of the outer jet nozzles 4 is equal to or larger than that of the inner jet nozzles 104. The outer jet nozzles 4 are arranged in essentially annular fashion within the nozzle carrier 3 and form an outer ring. The inner jet nozzles 104 are also arranged in annular fashion within the nozzle carrier 3. The inner jet nozzles 104 form an inner ring which is arranged concentric with the outer jet nozzle ring.

(13) FIGS. 2 and 3 merely show examples for the arrangement of jet nozzles 4, 104 within a jet burner 1, 101. Alternative arrangements are of course also possible, as is the use of a different number of jet nozzles 4, 104. In addition, the burner 1, 101 can comprise a pilot burner.

(14) FIG. 4 shows a section through a part of a jet burner 15 according to the invention, in which the jet nozzles 16 are arranged on a base plate 17, wherein the base plate 17 has cooling ducts 18 that can for example be cast directly in the base plate 17 when use is made of a casting process. It is then also possible for the jet nozzles 16, which form the main burner (premix burner) to be directly cast at the same time. The base plate 17 is cooled via the cooling air ducts 18.

(15) On the hot gas side, the base plate 17 can be complemented by a thermal barrier coating 19. By virtue of the combination of thermal barrier coatings 19 and effective cooling, it is possible under certain circumstances to do without, for example, nickel-based alloys. However, even when a nickel-based alloy is used, a reduction in costs is to be expected since substantially less material is necessary for a cast part.

(16) As further represented in FIG. 4, the cooling air 20 can be drawn either from the annular duct 13 or from the plenum 21 upstream of the base plate 17. When drawing from the annular duct 13, the cooling air 20 is fed to the cooling duct 18 via openings 22 on a circumferential rim 23 of the base plate 17. When drawing from the plenum 21, the cooling air 20 is fed to the cooling duct 18 via openings 24 on the cold gas side 10 of the base plate 17. After cooling the base plate 17, the cooling air 20 does not pass directly into the combustion chamber 7 but is fed to the pilot burner (cf. FIG. 6).

(17) As a consequence of the high flow speeds in the jet nozzles 16 (substantial drop in static pressure), there is here a strong pressure drop which can be used to equip the cooling ducts 18 with elements 26 for increased heat transfer (e.g. ribs or dimples 36) and/or for flow guiding (e.g. spoilers 35) (cf. FIG. 7).

(18) If the pilot draws the quantity of air required for its operation essentially via the cooling air ducts 18, a relatively high quantity of air is available (approx. 5-12% of the total available quantity of air 14), i.e. the cooling ducts 18 must in this case be accordingly large in order that the desired pilot air split, i.e. that fraction of the air supplied to the pilot with respect to the total quantity of air 14, is also achieved at the predefined differential pressure. In this case, the cooling ducts 18 were equipped with no or only a few ribs or similar elements 26. The required cooling effect is brought about by means of the increased mass flow rate.

(19) FIG. 5 shows a further possibility for drawing cooling air. In the case shown, the cooling air for the base plate 17 (or at least part of the cooling air) is drawn from the boundary layer at the redirection 30 from the annular duct 13 into the plenum 21. Drawing air in this manner means that the boundary layer is stabilized and remains attached for longer. This results in a lower redirection pressure loss. The pressure gained can be used e.g. for a higher jet velocity. The cooling air 20 passes into the cooling duct 18 of the base plate 17 via a cooling air line 32 which is arranged in the wall 31surrounding the jet nozzles 16 and adjoining the base plate 17of the nozzle carrier, is open toward the cold gas side 10 of the jet burner 15 and discharges into the base plate 17.

(20) FIG. 6 shows a further embodiment of the cooling concept according to the invention, in which air flows through a cooling duct 18, wherein the cooling duct 18 extends in the manner of a cavity approximately over the entire surface of the base plate 17 and wherein the cooling air 20, after flowing through the cooling duct 18, is supplied to the pilot burner 33 as pilot air 27. In this case, the pilot burner 33 is supplied with air directly and exclusively via the cooling duct 18.

(21) The circumferential wall 34, which extends beyond the cold gas side 10 of the base plate 17, approaches a central axis 2 of the jet burner 15 with increasing distance from the base plate 17. This wall 34 and thetypically cylindricalouter casing part 12 surrounding it then form a type of diffuser, which slows the airflow 14 provided by the compressor and the pressure advantageously increases.

(22) FIG. 7 shows a section, perpendicular to the central axis 2, through a jet burner 15, according to the invention, which can advantageously be created by means of a sheet metal construction since the cooling duct 18 extends essentially over the base area of the base plate 17, where relevant interrupted only by supporting elements. In the present example of FIG. 7, the cooling air 20 is guided from radially outside to radially inside between the hot gas side 9 and the cold gas side 10 of the base plate 17 (the pilot burner is not shown). In that context, the cooling air 20 flowing inward to the pilot must flow around the jet nozzles 4 of the premixed passages of the main burner 25.

(23) In order to avoid or at least minimize wake regions behind the jet nozzles 4, it is possible to introduce into the flow path elements 26 for increasing heat transfer and/or for flow guiding, as shown in FIG. 7 with the spoilers 35 or dimples 36.