PILOT CONUS COOLING

Description

[0001] The invention relates to a pilot cone for use in a burner arrangement, as well as a burner arrangement.

[0002] Equipping a central pilot burner with a cone for flame shaping is a widespread measure. Typically, such a pilot cone is cooled. Cooling air is usually directed at the rear of the pilot cone or through cooling channels within the pilot cone. It is common practice for the cooling air to be directed into the combustion chamber downstream of the pilot cone. This is considered unfavorable with regard to reducing NOx emissions. For a high-temperature combustion system, closed cooling with reuse of the cooling air in the pilot burner is necessary.

[0003] A pilot cone according to the state of the art is known from US 2019 / 086088 A1.

[0004] With closed cooling, the pilot cone is typically cooled by an integrated design with air, which is used as combustion air after the cooling task has been completed. For this purpose, it is known to equip the pilot cone with large-volume cooling channels that ultimately direct the cooling air to the pilot burner as combustion air.

[0005] However, these designs, with internal ducts for an airflow significantly larger than necessary for the cooling task, can no longer be described as simple. The complex and relatively large structures are neither cost-effective to manufacture nor are lifetime targets easily met. Aside from complexity and cost, the performance values ​​are also unsatisfactory.

[0006] The object of the invention is to provide a pilot cone in which cooling air and purge air consumption are as low as possible and which is also as simple and cost-effective to manufacture as possible. A further object of the invention is to provide a burner assembly with a pilot cone. Finally, it is an object of the invention to provide a corresponding method for operating such a burner assembly.

[0007] The generic pilot cone is intended for use in a burner arrangement. The pilot cone has a conically shaped shell that widens downstream along a burner axis. A plurality of cooling air passages are arranged in the shell to enable cooling of the shell. Furthermore, the pilot cone has an inner wall that extends upstream from the upstream end of the shell. An annular gap is arranged along the radially outer side of the inner shell, through which cooling air can be supplied. A plurality of cooling air openings are required on the shell adjacent to the annular gap to establish a connection between the annular gap and the cooling air passages.Thus, during operation of the burner arrangement, cooling air is guided outside the inner wall through the annular gap and through the cooling air openings and through the cooling air passages, thus cooling the jacket.

[0008] To enable optimal adjustment of the cooling air flow to ensure adequate cooling of the casing with the lowest possible cooling air consumption, an outer wall is arranged on the radially outer side, spaced from the inner wall. This wall defines the annular gap on the radially outer side and also extends upstream from the casing. This allows for targeted cooling air flow to the cooling air openings.

[0009] Thus, an annular gap is formed on the pilot cone by two, preferably coaxial, radially inner and radially outer walls arranged on the shell and extending upstream in the circumferential direction, over which the air supplied to the pilot cone for cooling is distributed according to its use.

[0010] To optimally adjust the cooling air flow, it is further provided that more cooling air is supplied through the annular gap than the casing requires. The balancing and thus the optimal adjustment of the cooling air flow in the cooling air passages is made possible by providing the inner wall with a plurality of openings. This results in a division of the air flow supplied through the annular gap into a flow through the openings on the one hand, and a flow of cooling air through the cooling air openings into the cooling air passages of the casing on the other.

[0011] By exploiting the design possibilities offered by additive manufacturing, it is possible to produce a pilot cone with integrated cooling. The pilot cone is therefore a compact component that can be easily integrated into an existing burner and enables long service life. The complexity of the cooling air duct is completely concealed within the pilot cone and can be advantageously manufactured using additive manufacturing methods. The cooling air flow is limited to that required for cooling, allowing more air to be available for premixing with the fuel.

[0012] To optimally adjust the cooling air flow through the passages, the sum of the cross-sectional areas of all openings is larger than the sum of the cross-sectional areas of all cooling air openings on the pilot cone shell. By selecting the size of the cross-sectional areas of the openings, the amount of air not required for cooling the pilot cone can be separated.

[0013] It is advantageous if the cooling air flow supplied to the casing can be adjusted by appropriately dimensioning the cooling air openings. In this case, the sum of the cross-sections of the cooling air openings must be smaller than the sum of the cross-sections of the cooling air passages that run parallel to the flow path.

[0014] In a further advantageous embodiment, the opening cross-sections of the respective cooling air openings are smaller than the cross-sections of the respective cooling air passages. Thus, in this embodiment, the openings, which essentially represent the inlet openings into the cooling air duct in the pilot cone, are the smallest passages in the system and can trap particles that could clog subsequent cooling channels. They are considered an integrated filter device.

[0015] In a particularly advantageous manner, the number of cooling air openings exceeds the number of cooling air passages running parallel in terms of flow. This makes it possible to select a small cross-section of the individual cooling air openings relative to the cross-section of the cooling air passages, thus preventing clogging of the cooling air passage by particles.

[0016] In an advantageous embodiment of the invention, an annular distributor is arranged in the jacket of the pilot cone, into which the circumferentially arranged cooling air openings open to distribute the cooling air evenly over the circumference of the pilot cone. This ensures that, even if individual cooling air openings become blocked, a reasonably even distribution of the cooling air flow to the cooling air passages can be ensured. Cooling air passages are provided to branch off from the distributor.

[0017] The arrangement of the pilot cone in the burner assembly is advantageously enabled if the pilot cone has a centering collar for accommodating a pilot burner. The centering collar is arranged upstream of the jacket, radially within the inner wall. Particularly advantageously, the centering collar forms a cylindrical mating surface.

[0018] To ensure the pilot burner fits optimally into the centering collar, it is also advantageous to provide an annular groove between the centering collar and the casing. This groove is designed to be open toward the burner axis.

[0019] This further enables the advantageous arrangement of sealing air outlets in the annular groove. The sealing air outlets form the end of cooling air passages, allowing the cooling air supplied through the cooling air openings to flow out through the sealing air outlets. These outlets are advantageously distributed equidistantly around the circumference, resulting in a uniform supply of sealing air in the area where the pilot cone interfaces with the pilot burner.

[0020] Furthermore, it is advantageous if the sealing air outlets are inclined. This allows for a swirling pilot burner flow and also allows the flow to adhere to the surface of the shroud downstream of the annular groove, thus preventing flow separation.

[0021] Advantageous cooling air guidance in the casing is achieved by using first cooling air passages extending downstream and second cooling air passages extending upstream, offset in the circumferential direction. The first cooling air passages are connected to the second cooling air passages via the first transverse passages at the downstream end of the casing. The cooling air is supplied from the cooling air openings to the first cooling air passages. After being deflected at the first transverse passages, the cooling air flows through the second cooling air passages back to the upstream end of the casing. In the simplest form, the transverse passages extend in the circumferential direction.

[0022] If there is an advantageous distributor in the shell, the first cooling air passages begin at the distributor.

[0023] If there are sealing air outlets, this is advantageously located at the end of the second cooling air passages.

[0024] An advantageous deflection of the cooling air flow at the downstream end of the shroud is made possible if a first transverse passage connects at least two first cooling air passages and at least two second cooling air passages. If at least two first cooling air passages flow into a first transverse passage and at least two second cooling air passages branch off from the first transverse passage, two advantages arise. Firstly, a more even temperature distribution can be achieved over the circumference of the pilot cone. Secondly, if a cooling air passage becomes blocked, not an entire path fails immediately, but only the flow in one direction along an individual cooling air passage is disrupted or interrupted, while cooling air can continue to flow adjacently.

[0025] In conjunction with a first transverse passage, two second cooling air passages are advantageously arranged adjacent to one another between two first cooling air passages.

[0026] In order to ensure cooling air guidance even in the event of a possible restriction in the flow of a first cooling air passage, it is furthermore advantageous if adjacent first cooling air passages which are not connected to one another via a first transverse passage are connected to one another via second transverse passages.

[0027] However, it is particularly advantageous if, in the connection via the first transverse passage, two first cooling air passages are arranged adjacent to one another between two second cooling air passages.

[0028] Similarly, in order to ensure cooling air guidance even in the event of a possible restriction in the flow of a second cooling air passage, it is still advantageous if adjacent second cooling air passages, which are not connected to each other via a first cross passage, are connected to each other via a second cross passage.

[0029] The second cross passage is positioned upstream of the first cross passage in the direction of the combustion chamber axis. Thus, flow in the second cross passages is only relevant in cases where there is a restriction in the flow through the connected cooling air passages.

[0030] In an advantageous embodiment, the first and second cooling air passages have a round cross-section. While rectangular cooling air passages allow for larger channel cross-sections, round cooling air passages are more advantageous in terms of material stresses and service life.

[0031] In order to generally reduce the cooling air requirement, it is advisable if the inner surface of the jacket of the pilot cone, ie the combustion chamber side surface, is provided with a thermal insulation layer, as is generally the case.

[0032] The additive manufacturing method allows for the easy addition of additional features. Therefore, it may be useful to have at least three protruding prongs arranged on the outside of the pilot cone as a safety catch. This safety catch holds the pilot cone firmly in the main burner in the unlikely event of accidental detachment.

[0033] The specific design of the inner wall and - if present - the second wall is initially irrelevant. At least the inner wall of the burner arrangement, as intended, partially surrounds the pilot burner. For this purpose, in a preferred embodiment, the inner wall is designed such that it widens upstream from the jacket. This creates more space for the pilot burner. Inevitably, in this embodiment, the annular gap also widens upstream from the jacket of the pilot cone. In accordance with the contested arrangement of the second wall - if present - from the first wall, this wall has a correspondingly widening shape upstream.

[0034] The provision of a novel pilot cone enables the realization of a novel burner assembly according to the invention. This generic assembly initially comprises a centrally arranged pilot burner extending along a burner axis. A pilot cone is arranged at the downstream end of the pilot burner. Furthermore, the burner assembly comprises a main burner with a central opening. The pilot burner with the pilot cone is located therein. According to the invention, the pilot cone has a shape as previously described.

[0035] Advantageously, the contact point between the pilot burner and the pilot cone is designed as a sliding fit. A sliding fit is defined as a fit that is easy to join and also allows for varying thermal expansion along the burner axis.

[0036] It is particularly advantageous if the design of the contact point allows for leakage with a slight cooling air flow. This prevents a tight connection between the pilot cone and the pilot burner at the contact point due to excessive thermal loads and / or deposits, which prevents relative displacement, particularly due to different thermal expansions, and can lead to thermal stresses.

[0037] Furthermore, it is advantageous if the existing sealing air outlets in the pilot cone, especially in the annular groove, are directed toward an end section of the pilot burner immediately downstream of the contact point. This ensures optimal protection of the contact point. The cooling air from the pilot cone is thus reused after the pilot cone has been cooled to purge the contact point between the pilot burner and the pilot cone. Otherwise, air would have to be supplied separately to this area.

[0038] It is advantageous if the annular groove in the pilot cone is partially covered by an end section of the pilot burner. This allows for a protected position of the contact point, especially the sliding seat, between the pilot cone and the pilot burner. Furthermore, this creates an annular cavity that facilitates further cooling air flow. The supplied cooling air then exits from a sealing air gap between the upstream end of the pilot cone jacket and the end section of the pilot burner.

[0039] An advantageous attachment of the pilot cone is achieved when the pilot cone is attached to a pilot cone support. The connection is preferably made at the upstream end of the inner wall. The inner wall can, for example, seamlessly transition into the pilot cone support.

[0040] Furthermore, it is particularly advantageous if the pilot cone support also allows for the cooling air to be guided. For this purpose, a cooling air supply runs radially outside the pilot cone support, which merges into the annular gap. In a simple and advantageous manner, the pilot cone support is formed in the shape of a cylinder.

[0041] To support the main burner, a main burner support is advantageously arranged radially outside the pilot cone support. If a cooling air supply is provided radially outside the pilot cone support, the main burner support limits the cooling air supply on the radially outer side.

[0042] It is advantageous if the outer wall is mounted on the main burner support at its upstream end. This can be done either by a fixed connection / mounting or by a sliding fit, which allows for varying thermal expansion.

[0043] To utilize the cooling air supplied to the pilot cone through the annular gap as combustion air, an annular chamber is advantageously arranged on the side of the inner wall facing the burner axis. This annular chamber is fluidly connected to a pilot burner inlet. This allows the air volume supplied for cooling the pilot cone to be divided into a portion required for cooling the pilot cone, flowing through the cooling air openings, and an excess portion, flowing through the apertures, which is fed to the pilot burner for combustion.

[0044] The object directed to a method is achieved by a method for cooling a pilot cone of a burner arrangement with a pilot burner, wherein the pilot cone comprises a downstream widening jacket and is arranged immediately downstream of the pilot burner and is fluidically connected thereto, in which cooling air is guided inside the jacket and cooling air leaving the jacket flushes an interface between the pilot burner and the pilot cone.

[0045] Advantageously, cooling air is supplied to the jacket of the pilot cone via a first cooling air passage and returned via a second cooling air passage adjacent to the first cooling air passage. The first and second cooling air passages are connected to each other near the downstream end of the pilot burner via comparatively short first transverse passages. In particular, the cooling air is guided along the shortest path from the annular distributor at the upstream end to near the downstream end of the pilot cone and from there returned along the shortest path. This results in efficient and as uniform as possible cooling and temperature distribution in the pilot cone.

[0046] Furthermore, it is advantageous if, in the case of a blocked second cooling air passage, cooling air is recirculated via a second cooling air passage adjacent to the blocked second cooling air passage.

[0047] The main advantages of the invention are in particular a compact pilot cone without any hindrance to expansion with a uniform component temperature and the resulting long component service life.

[0048] Furthermore, closed air cooling of the pilot cone can be achieved by flushing the interface between the pilot cone and the pilot burner, in which the cooling air already used to cool the pilot cone jacket is reused. A particularly advantageous feature here is that the cooling air escaping at the contact point between the pilot cone and the pilot burner can also be used as combustion air.

[0049] A further advantage is the improved insensitivity to blockage of cooling air openings or individual cooling air passages and an unimpaired guarantee of advantageous cooling of the jacket of the pilot cone.

[0050] The complex internal channel structure is advantageously enhanced by the use of additive manufacturing. This allows the component to be constructed very efficiently in terms of cooling performance and cooling air balance. Another advantage of additive manufacturing is the very short production times.

[0051] The invention is explained in more detail by way of example with reference to the drawings. They show schematically and not to scale: Fig. 1 a perspective view of a pilot cone in longitudinal section; Fig. 2 a section of the pilot cone from Fig. 1 with the pilot burner arranged therein; Fig. 3 a section of a burner arrangement with the pilot cone from Fig. 1 as well as a pilot burner and, in sections, a main burner; Fig. 4 again the pilot cone from Fig. 1 with a section through the second cooling air passages; Fig. 5 again the pilot cone from Fig. 1with a section through the first cooling air passages; Fig. 6 a further detailed view of the pilot cone in the area of ​​the cooling air openings and the cooling air penetrations; Fig. 7 the cooling air duct in the jacket of the pilot cone; Fig. 8 schematically the cooling air duct in the jacket starting from the cooling air openings; Fig. 9 schematically the cooling air duct in the area of ​​the transverse passages.

[0052] In the Fig. 1 An exemplary embodiment of a pilot cone 01 according to the invention is shown in a perspective view in longitudinal section. The pilot cone 01 has a jacket 04 that widens downstream in the main flow direction of fuel and air. The term "upstream" always refers to the side opposite a combustion chamber following the pilot cone, while "downstream" always refers to the side facing the combustion chamber.

[0053] An inner surface 16 of the jacket 04 of the pilot cone 01 is provided with a thermal insulation layer 17. A cooling air duct 05 (not visible in this view) runs inside the jacket 04.

[0054] An inner wall 07 extends upstream from the upstream end of the casing 11, which also widens as it does so. The outer wall 08 is located on the radially outer side, spaced apart from the inner wall 07. This creates an annular gap 06 between the inner wall 07 and the outer wall 08, which serves to guide the cooling air.

[0055] In the Fig. 2 A section of a burner arrangement with the pilot cone 01 and a pilot burner 03 arranged therein is sketched. On the side facing the burner axis 21, adjacent to the inner wall 07, radially outside the pilot burner 03, there is an annular chamber 26.

[0056] Essential to the invention is the distribution of the cooling air supplied through the annular gap 06, on the one hand, for cooling the jacket 04 and, on the other hand, for mixing with the combustion air supplied to the pilot burner 03. For this purpose, the inner wall 07 has a plurality of openings 09 distributed around the circumference, which establish a connection between the annular gap 06 and the annular chamber 26. The cooling air duct from the annular gap 06 into the jacket 04 of the pilot cone 01 is made of Fig. 6 and will be explained further below.

[0057] Also visible is a centering collar 17 at the upstream end of the casing 04, in which the pilot burner 03 is mounted in a contact point 23 with a sliding seat. The contact point 23 allows a relative displacement of the pilot burner 03 relative to the pilot cone 01 and thus prevents thermal stresses. Furthermore, the contact point 23 between the pilot burner 03 and the pilot cone 01, as a sliding seat, allows leakage of the cooling air from the annular chamber 26 and thus counteracts the sticking of the two components 01, 03 to one another at the contact point 23.

[0058] An annular groove 30 is located between the contact point 23 and the jacket 04 of the pilot cone. This is partially covered on the radially inner side by an end section of the pilot burner 03. This forms a circumferential cavity 29. A sealing air gap 28 is located between the end section of the pilot burner 03 and the upstream end of the jacket 04 of the pilot cone 01.

[0059] The Fig. 3 shows schematically and by way of example a section of a burner arrangement 02 with a central burner axis 21, comprising a main burner 19 and a pilot burner 03 arranged in the main burner 19. The pilot cone 01 is arranged directly downstream of the pilot burner 03.

[0060] The main burner 19 is mounted on the radially inner side via a main burner support 22. At the same time, this embodiment provides for the outer wall 08 of the pilot cone 01 to be mounted in the main burner support 22 at its upstream end, thus providing centering.

[0061] A pilot cone support 25 is located spaced apart from the main burner support 22 on the side facing the burner axis 21. The inner wall 07 of the pilot cone 01 adjoins the end of the pilot cone support 25. Several protruding prongs 18 are arranged on the outside of this 07, distributed around the circumference in this embodiment. These prevent displacement out of the main burner 19 if the pilot cone 01 becomes detached.

[0062] In this embodiment, the main burner support 22 and the pilot cone support 25 are cylindrical and arranged coaxially with each other, creating a fluidic separation. This creates a cooling air supply 24 between the main burner support 22 and the pilot cone support 25. The cooling air flowing through the cooling air supply 24 further cools the main burner support 22.

[0063] The cooling air supply 24 is optimized to generate the flow velocity required for heat transfer while maintaining low pressure loss. The high pressure gradient between the cooling air inlet and outlet of pilot cone 1 enables efficient cooling with a comparatively low air mass flow.

[0064] The outer cooling air supply 24 opens into the annular gap 06 of the pilot cone 01, which 06 is formed by the two coaxial radially inner and radially outer walls 07, 08 arranged on the casing 04, extending in the circumferential direction and inclined upstream. The radially inner wall 07 is connected to the pilot cone support 25, and the radially outer wall 08 is connected to the main burner support 22, so that a closed cooling air duct to the pilot cone 01 is formed between the main burner 19 and the pilot burner 03.

[0065] From the annular gap 06, the cooling air flows proportionally through the openings 09 in the inner wall 07 into the annular chamber 26 and subsequently to the main flow path of the combustion air supplied to the pilot burner to a pilot burner inlet 27.

[0066] The cooling air guide 05 in the jacket 04 of the pilot cone 01 is designed according to the Figures 4 to 9 explained in more detail - see in particular Fig. 7The cooling air duct 05 has a repeating pattern in its circumference, so that the Figures 4 to 6 , 8 and 9 obviously reveals the structure in the shell 04 of the pilot cone 01.

[0067] Distributed around the circumference near the upstream end of the shell 04 are a plurality of cooling air openings 10 - see Fig. 5 and 6 , which establish a connection from the annular gap 06 to the cooling air passages 12, 14 in the casing 04. An annular distributor 11 is arranged in the casing 04 of the pilot cone 01, into which the cooling air openings 10 arranged in the circumferential direction open. During operation of the burner arrangement 02, the air for cooling the pilot cone 01 initially flows through a plurality of cooling air openings 10, which are arranged distributed in the circumferential direction, into the said annular distributor 11.

[0068] First cooling air passages 12 branch off from the distributor 11 and extend within the casing 04 essentially downstream - see Fig. 5 and Fig. 8 .

[0069] At the downstream end of the shell 04, the first cooling air passages 12 each open into first transverse passages 13, which extend in the circumferential direction - see Fig. 9 From the first transverse passages 13, second cooling air passages 14 branch off, extending upstream - see Fig. 4 . In this embodiment, it is provided that two adjacent first cooling air passages 12 open into a first transverse passage 13 and two second cooling air passages 14 branch off from the first transverse passage 13.

[0070] The first and second cooling air passages 12, 14 are, as an advantageous and simplest design, round in cross-section.

[0071] The air thus flows through the first cooling air passages 12 to the front edge of the pilot cone 01 and flows there via first transverse passages 13 to adjacent second cooling air passages 14, which are provided for the return of the air to the interface with the pilot burner 03.

[0072] The first and second cooling air passages 12, 14, ie, the supply and return channels, are arranged alternately and adjacent second cooling air passages 14 are connected by second transverse passages 15 in order to allow a cooling air flow, albeit reduced, through unblocked sections in the unlikely event of a blocked cooling passage.

[0073] This emergency cooling property is intended to counteract further damage to the pilot cone 01 after a damage with blocked cooling passages 12, 14, so that a reasonably uniform cooling can be ensured even if a single cooling air passage 12, 14 is blocked.

[0074] The cross-sections of the cooling air openings 10 are selected to be smaller than the cross-sections of the first and second cooling air passages 12, 14 or the first and second transverse passages 13, 15, so that a filter function is obtained at the inlet to the cooling air duct 05.

[0075] The second cooling air passages 14 open into the annular groove 30 or into the circumferential cavity 29 at the contact point 23 of the pilot cone 01 with the pilot burner 03 - see Fig. 4 (also Fig. 2 ). This means that after flowing through the pilot cone 01, the cooling air enters a circumferential cavity 29, which seals the interface between the pilot cone 01 and the pilot burner 03 against the penetration of hot gas. The cooling air then mixes with the pilot burner flow.

[0076] The passages of the second cooling air passages 14 near the outlet, referred to as sealing air outlets 32, are arranged equidistantly around the circumference in the annular groove 30 and oriented such that, during operation of the burner assembly 02, they are inclined in the direction of a swirling pilot burner flow in order to ensure that the flow adheres downstream of the annular groove 30 along the casing 04 and to prevent separation. As a side effect of the overlap, the sealing air outlets 32 are protected.

[0077] The purging of the sealing air gap 28 at the contact point 23 between the pilot cone 01 and the pilot burner 03, which is necessary for safety reasons, involves reusing the cooling air. Thus, the cooling process is considered closed or cooling air neutral. The high pressure gradient between the cooling air inlet and outlet achieves a high cooling effect with a low cooling air mass flow.

Claims

1. Pilot cone (01) for use in a burner arrangement (02), having a covering (04) which widens downstream along a burner axis and which is passed through by a plurality of cooling air passages (12, 14), and having an internal wall (07) which extends upstream from the upstream end of the covering (04), having an annular gap (06) which extends at the radially external side along the internal wall (07), and having a plurality of cooling air openings (10) which produce a connection from the annular gap (06) to the cooling air passages (12, 14), and having an external wall (08) which extends upstream with spacing from the internal wall (07) from the covering (04) and which delimits the annular gap (06) at the radially external side, wherein the internal wall (07) has a plurality of apertures (09) ; wherein the total of the cross sectional surface-areas of all the apertures (9) is greater than the total of the cross sectional surface-areas of all the cooling air openings (10).

2. Pilot cone (01) according to Claim 1, wherein the total of the cross sectional surface-areas of all the cooling air openings (10) is smaller than the total of the cross sectional surface-areas of all the cooling air passages (12, 14); and / or wherein the cross sectional surface-area of each individual cooling air opening is smaller than the cross sectional surface-area of the cooling air passages (12, 14).

3. Pilot cone (01) according to Claim 1 or 2, wherein an annular distributor (11) which is connected to the cooling air openings (10) and to cooling air passages (12) is arranged in the covering (4), from which annular distributor (11) in particular first cooling air passages (12) branch off.

4. Pilot cone (01) according to one of Claims 1 to 3, wherein a centering collar (17) is arranged upstream of the covering (04) in order to receive a pilot burner (03).

5. Pilot cone (01) according to Claim 4, wherein a circumferential annular groove (30), which is open toward the burner axis (21), is arranged between the covering (04) and the centering collar (17).

6. Pilot cone (01) according to Claim 5, wherein sealing air outlets (32) are arranged in connection with cooling air passages (14) in the annular groove (30), which sealing air outlets (32) are particularly inclined so that a cooling air flow which is partially tangential occurs; and / or which sealing air outlets (32) form in particular the end of the second cooling air passages (14).

7. Pilot cone (01) according to one of Claims 1 to 6, wherein first cooling air passages (12) extend inside the covering (04) downstream and second cooling air passages (14) extend upstream, wherein adjacent cooling air passages (12, 14) are connected to each other via first transverse passages (13).

8. Pilot cone (01) according to Claim 7, wherein at least two first cooling air passages (12) and at least two second cooling air passages (14) are connected to each other via a first transverse passage (13); or wherein two adjacent first cooling air passages (12) and two second cooling air passages (14) are connected to each other via a first transverse passage (13); or wherein two adjacent second cooling air passages and two first cooling air passages are connected to each other via a first transverse passage.

9. Pilot cone (01) according to Claim 8, wherein mutually adjacent cooling air passages (14) (which are not connected via first transverse passages) are connected to each other via second transverse passages (15) which are offset upstream relative to the first transverse passages.

10. Pilot cone (01) according to one of Claims 1 to 9, wherein the internal wall (07) and the annular gap (06) and in particular the second wall (08) widen upstream.

11. Burner arrangement (02) having a burner axis comprising a main burner (19) and a pilot burner (03) which is arranged centrally therein (19) and a pilot cone (01) which is arranged at the downstream end of the pilot burner (03), characterized by a configuration according to one of the preceding claims.

12. Burner arrangement (02) according to Claim 11, wherein a contact location (23) between the pilot burner (03) and the pilot cone (01), in particular the centering collar (17), is in the form of a sliding seat, wherein in particular the contact location allows a small cooling air flow.

13. Burner arrangement (2) according to Claim 12, wherein the annular groove (30) is covered at least partially by an end portion of the pilot burner (03) and a circumferential cavity (29) is formed.

14. Burner arrangement (02) according to one of Claims 11 to 13, wherein the pilot cone (01), in particular the internal wall (07), is fixed to a pilot cone carrier (25), wherein in particular a cooling air supply (24) extends radially outside the pilot cone carrier (25) and merges into the annular gap (06).

15. Burner arrangement (2) according to Claim 14, wherein a main burner carrier (22) is arranged radially outside the pilot cone carrier (25), in particular radially outside the cooling air supply (24), on which main burner carrier (22) in particular the external wall (08) is supported.

16. Burner arrangement (2) according to one of Claims 11 to 15, wherein the apertures (09) lead to an annular chamber (09) which is connected to a pilot burner inlet (27) of the pilot burner (03) in technical flow terms.