EP3132202B1 - Bypass heat shield element - Google Patents

Description

The invention relates to a heat shield element, in particular for lining a combustion chamber. The invention further relates to an annular combustion chamber and a gas turbine plant.

In part-load operation of a gas turbine, the combustion temperature drops in the combustion chamber. At the same time, the relevant for the carbon monoxide emissions primary zone temperature drops. When these fall below a minimum value, carbon monoxide emissions are increasingly generated and the limit of the usable carbon monoxide emission compliant partial load range of the gas turbine is reached.

In the presence of a legal carbon monoxide emission limit, the gas turbine operator may be forced to shut down its gas turbine if it is unable to further reduce its gas turbine power without exceeding the carbon monoxide emission limit.

The supply of bypass air into the combustion chamber, ie from compressor discharge air, which is diverted in front of the burner and guided into the combustion chamber behind the combustion zone, is remedied. However, the walls of high temperature gas reactors, such as pressurized gas turbine combustors, require suitable shielding of their support structure against attack by the hot gas. Due to their high temperature resistance, corrosion resistance and their low thermal conductivity compared to metallic materials, ceramic materials are particularly suitable for building up a heat shield shielding the support structure. Such a heat shield is for example in EP 0 558 540 B1 and would have to be modified accordingly in the implementation of a bypass of the compressor discharge air. The simple introduction of Openings do not solve the problem because the flow of hot gas within the combustion chamber heats the surface of the ceramic heat shields and the bypass air on their side faces provides for strong cooling. This creates high temperature gradients and associated stresses within the shields, which in operation cause cracks and fractures and the loss of heat shields.

A supply of a bypass air flow to a heat shield element according to the WO 2013/135702 A2 , which discloses the preamble of claim 1, be enabled. For this purpose, the heat shield element has a wall with a hot side facing the combustion chamber and an opposite cold side. A circumferential edge extends beyond the cold side on the back. It is provided that in the peripheral edge a plurality of bores are introduced, can flow through the cooling air into the combustion chamber. Furthermore, it is provided that at a distance from the wall, a second partial wall is present, which extends between two opposite edge portions. However, a downstream edge portion of the peripheral edge extends only to the partial wall and not beyond. At the upstream end of the partial wall approximately centrally in the heat shield element, a partition wall is arranged, which extends from the partial wall to the rear height of the two adjacent edge portions. This also makes it possible to guide a bypass air flow on the partial wall, which can then emerge downstream between the opposite edge portions.

A disadvantage of the previous solution, however, is that for the advantageous inflow of the bypass air, an offset in the heat shield elements is necessary or a higher pressure loss must be accepted by a deflection in a subsequent gap in purchasing.

An object of the invention is therefore to provide a heat shield element which allows the supply of bypass air, at the same time high life and as possible easy and inexpensive to manufacture and assemble. Another object of the invention is to provide an annular combustion chamber with a corresponding heat shield. Furthermore, it is an object of the invention to provide a gas turbine plant for the part-load operation.

According to the invention, these objects are achieved by the heat shield element according to claim 1, the annular combustion chamber according to claim 8 and the gas turbine plant according to claim 13. Advantageous developments of the invention are defined in the respective dependent claims.

The generic heat shield element is used in particular for use as a lining of a combustion chamber. In this case, the heat shield element initially comprises a wall which has a hot side which can be acted upon by a hot medium and a cold side which is opposite to the hot side. Furthermore, the heat shield element comprises an edge adjacent to the wall and surrounding the wall. In this case, the edge extends from the hot side pointing away raised above the cold side. Regardless of the concrete shape of the wall viewed in a plan view of the hot side, the edge can be divided into two opposing first edge portions. At one end of the wall is a second edge portion, which connects the two first edge portions with each other and extends substantially transverse to the first edge portions. Opposite to the second edge portion is a third edge portion, which also connects the two first edge portions with each other and extends substantially transverse to the first edge portions.

According to the invention it is now provided that within the heat shield element a breakthrough is created, through which the supply of bypass air is made possible in the combustion chamber interior. For this purpose, the wall has at least one opening gap, whereby the wall in a first wall portion on one side of the opening gap and a second wall portion the other side of the opening gap is divided. Furthermore, it is provided that adjoins the second wall portion adjacent to the opening gap from the hot side pioneering partition. In this respect, the second wall section on the cold side is surrounded by sections of the two first edge sections, the second edge section and the partition wall arranged opposite the second edge section. By contrast, the first wall section is surrounded by likewise the two first edge sections in sections, the third edge section and the opening gap arranged opposite the third edge section adjacent to the dividing wall.

As a result, two separate first and second chambers are formed on the cold side of the wall, wherein the first chamber has an opening gap from the cold side to the hot side. By such a double-chamber concept, the interior of the heat shield element is divided into two parts. The first chamber acts as an extension of the bypass channel. The heat shield element fits homogeneously into the bypass. Characterized in that the opening gap directly adjacent to the partition wall in particular a small distance between a bypass channel and the Öfftsspalt a homogeneous flow pattern is promoted with low pressure drop across the opening gap.

In a further advantageous embodiment of the invention, the opening gap extends along the entire partition between the two opposite first edge portions, so that a uniform bypass flow with sufficient mass flow can be achieved.

The shape or the course of the peripheral edge and the partition on the cold side is initially irrelevant. In this respect, the edge portions and the partition wall to each other and / or within the sections kinks or jumps and thus have a different height on the cold side. However, it is advantageous if the circulating Edge and the partition extends to a remote from the cold side free end. In this case, the free end corresponds to a surface which is at a distance from the hot side or from the cold side (without kinks or jumps).

It is particularly advantageous if the free end is planar. The planar shape of the heat shield element on the rear facing away from the hot side favors both the assembly and the production.

In yet another advantageous embodiment, the partition wall is inclined towards the opening gap. Thus, when viewing the heat shield element from the hot side, the partition wall is located over the opening gap in sections. Thus, a neutral discharge angle of the bypass flow can be realized when entering the combustion chamber, since the bypass air must otherwise flow against the combustion gas. In addition, the gap would otherwise open to the flame and would provoke the entry of hot gas.

It is advantageous if the partition wall has a plurality of bores whose axes are directed onto the surface of the cold side of the first wall section. If the second chamber is designed comparatively flat, there can be a conventional, large-scale impact cooling there. The used cooling air causes in the absence of bypass current in addition to blocking the opening gap. For this purpose, the cooling air can flow from the second chamber through the holes in the partition into the first chamber.

It is expedient if in the second chamber, starting from the second wall portion, a fastening device is arranged, which advantageously extends perpendicularly pointing away from the wall of the hot side.

Furthermore, it is expedient if the heat shield element is made of metal. Typically, such a heat shield element is realized as a cast component.

A generic annular combustion chamber comprising an outer shell and a number of heat shield elements, which are releasably secured to the interior of the outer shell facing the combustion chamber interior. Furthermore, the annular combustion chamber comprises a so-called Bypassplenum, extending over the circumference of the outer shell annular channel through which an air bypass flow is passed in the bypass mode. The annular channel can be supplied via openings of the bypass air flow, wherein the annular channel has a combustion chamber interior facing annular gap through which the bypass air flow can be passed to the combustion chamber interior. Here, the annular channel and the annular gap can be performed circumferentially. If a fairly uniform distribution of the bypass air flow is ensured over the circumference, the annular channel and / or the annular gap can also be interrupted several times and thus consist of individual segment sections.

A novel annular combustion chamber is created by the use of a plurality of the above-described invention and / or heat shield elements advantageous for this purpose.

It is particularly advantageous if the heat shield elements are arranged such that the first chambers come to rest on the annular gap. In this respect are on one side of the annular gap, the partition and on the other side of the annular gap of the third edge portion. This allows a particularly advantageous flow of the bypass air flow from the annular gap through the first chamber and through the opening gap in the individual heat shield elements.

In an advantageous embodiment of the invention, the outer shell has openings for the impact cooling of the heat shield elements.

It is expedient if openings for the impingement cooling of the first wall section are arranged in the first chamber in the annular channel of the outer shell and tubes in these openings are arranged, which extend to the hot side over the outer shell out into the first chambers. As a result, cooling air can be directed to the first wall section of the first chamber. Thus, this area is both convective, as well as cooled by impact cooling.

Furthermore, it is particularly advantageous if a cross flow of the bypass air flow and / or the cooling air is avoided. For this purpose, it is provided in a first variant that the heat shield element rests at least in sections with the free end on the outer shell. Due to the support, a transverse flow between the free end and the outer shell is largely prevented. Obviously, it is particularly advantageous if the support is provided on the peripheral edge and along the partition wall on the outer shell.

In a second variant, a sealing means between the free end of the heat shield element and the outer shell is provided. Likewise, it is advantageous if the sealant is not present in sections, but circumferentially. In this case, it can furthermore be advantageously provided that the sealing means is made of an elastic material, so that despite slight deviation in the shape of the free end and / or the outer shell as well as in vibrations a reliable tightness is achieved. For secure fixation of the sealant this is installed in the peripheral edge or in the partition and is beyond the free end.

In addition, it can be provided that the first variant and the second variant is combined for sealing by sections an immediate support of the free end is provided on the outer shell and sections, especially in areas with higher pressure difference, a sealant between the free end and the Outer shell is present.

The object directed to a gas turbine plant is achieved by a gas turbine plant having an annular combustion chamber according to the invention.

• Figur 1 die Kaltseite eines Hitzeschildelements nach der Erfindung mit einer zweiten Kammer im Vordergrund,
• Figur 2 die Kaltseite eines Hitzeschildelements nach der Erfindung mit einer zweiten Kammer im Hintergrund,
• Figur 3 ein Hitzeschildelement im Schnitt,
• Figur 4 die Heißseite eines Hitzeschildelements nach der Erfindung,
• Figur 5 das Bypass-Konzept,
• Figur 6 das Kühlluftmanagement,
• Figur 7 ein Ausschnitt aus der Ringbrennkammer mit Hitzeschildelementen nach der Erfindung und
• Figur 8 eine Darstellung einer erfindungsgemäßen Gasturbine in einem Längsschnitt gemäß einem Ausführungsbeispiel.

The invention will be explained in more detail by way of example with reference to the drawings. Shown schematically and not to scale:

• FIG. 1 the cold side of a heat shield element according to the invention with a second chamber in the foreground,
• FIG. 2 the cold side of a heat shield element according to the invention with a second chamber in the background,
• FIG. 3 a heat shield element in section,
• FIG. 4 the hot side of a heat shield element according to the invention,
• FIG. 5 the bypass concept,
• FIG. 6 the cooling air management,
• FIG. 7 a section of the annular combustion chamber with heat shield elements according to the invention and
• FIG. 8 an illustration of a gas turbine according to the invention in a longitudinal section according to an embodiment.

The FIGS. 1 to 4 show schematically and by way of example a metallic heat shield element 1 according to the invention, with a wall 3, which has a hot medium acted upon by a hot side 4 and a hot side 4 opposite cold side 5. The FIGS. 1 to 3 show the cold side 5 and the FIG. 4 shows the hot side 4.

Adjacent to the wall 3 is an encircling edge 6 extending beyond the plane of the cold side 5 and having a free end 7 remote from the cold side 5. The rim comprises Here, the two first opposite edge portion 56 and a transversely to the first edge portions 56 extending second edge portion 57 and a 57 opposite thereto third edge portion 58. A partition 8 extends from the cold side 5 of the wall 3 to the height of the free end 7 between two opposite, formed by the edge 6 sides 9, so that on the cold side 5 of the wall 3 two separate first and second chambers 10, 11 are formed and the first chamber 10 has an opening gap 12 from the cold side 5 to the hot side 4, which is connects directly to the partition wall 8 and extends along the entire partition 8. As a result, the wall 3 is divided into two sections, namely once into a first wall section 51 and a second wall section 52. The partition 8 is inclined to the opening gap 12 and has a plurality of bores 13, whose axes 14 are directed to the surface of the cold side 5 in the first chamber 10.

In the FIGS. 1 to 3 it is further shown that in the second chamber 11, a fastening device 15 is arranged, which extends substantially perpendicularly from the wall 3 away. An assembly of the heat shield element 1 takes place, for example, via a plate spring assembly connected to the fastening device 15.

The FIGS. 5 and 6 show a section through an annular combustion chamber 2 with a number of heat shield elements 1 according to the invention. Based on FIG. 5 the bypass concept should be explained. The annular combustion chamber 2 of FIG. 5 comprises an outer shell 16, a number of heat shield elements 1 according to the invention, which are detachably secured to the inside of the outer shell 16, and a designated as Bypassplenum, extending over the circumference of the outer shell 16 annular channel 17 through which in the bypass mode, an air By-pass current is passed, with an annular gap 18 to the combustion chamber interior 19 out. The heat shield elements 1 are now arranged such that their first chambers 10 are located on the annular gap 18 come. In addition to the metallic heat shield elements 1 according to the invention, the combustion chamber 2 upstream of the metallic heat shield elements 1 comprises a plurality of rows of ceramic heat shield elements 24, of which in the FIG. 5 only one is indicated, as well as downstream of the metallic heat shield elements 1 according to the invention, a number of further metallic heat shield elements 25, but without opening gaps 12th

FIG. 6 explains the cooling air management. Bypass 26 passes from the annular channel 17 in the first chamber 10 of the heat shield elements 1 and passes through opening gaps 12 in the combustion chamber interior 19. The outer shell 16 has first openings 20 for the impingement cooling 27 of the heat shield elements 1, in particular for the second chambers 11. Durch die Bores 13 in the partition 8, the air used for baffle 27 of the second chamber 11 can continue to be used to block the opening gap 12 against hot gas from the combustion chamber interior 19 (see, sealing air 28).

Furthermore, second openings 21 for the impingement cooling 29 of the first chambers 10 are provided in the annular channel 17 of the outer shell 16. In these second openings 21, tubes 22 are arranged, which extend into the first chambers 10. This arrangement serves for the impingement cooling 29 of the first chambers 10.

FIG. 7 shows a section of the annular combustion chamber 2 with heat shield elements 1 according to the invention, ceramic heat shield elements 24 and other metallic heat shield elements 25 in plan view.

The FIG. 8 shows schematically and by way of example a gas turbine plant 23 according to the invention in a longitudinal section. This comprises a compressor section 30, a combustion chamber section 31 and a turbine section 32. A shaft 33 extends through all sections of the gas turbine installation 23. In the compressor section 30, the shaft 33 is provided with rings of compressor blades 34 and in the turbine section 32 Wreaths of turbine blades 35 equipped. Wheels of compressor guide vanes 36 are located between the rotor blade rings in the compressor section 30 and wreaths of turbine guide vanes 37 in the turbine section 32. The guide vanes extend from the housing 38 of the gas turbine installation 23 substantially in the radial direction to the shaft 33.

In operation of the gas turbine plant 23, air 39 is drawn in through an air inlet 40 of the compressor section 30 and compressed by the compressor blades 34. The compressed air is supplied to a combustion chamber 2 arranged in the combustion chamber 2, which is configured in the present embodiment as an annular combustion chamber 2. A number of heat shield elements 1, 24, 25, which are releasably secured to the inside of the outer shell 16, forms a heat shield 41. In the annular combustion chamber 2, a gaseous or liquid fuel is injected via at least one burner 42. The resulting air-fuel mixture is ignited and burned in the combustion chamber 2. Along the flowpath 43, the hot combustion exhaust gases flow from the combustor 2 into the turbine section 32, where they expand and cool, imparting momentum to the turbine blades 35. The turbine guide vanes 37 serve as nozzles for optimizing the momentum transfer to the rotor blades 35. The rotation of the shaft 33 caused by the momentum transfer is used to drive a load, for example an electric generator. The expanded and cooled combustion gases are finally discharged through an outlet 44 from the gas turbine plant 23.

Claims (13)

1. Heat shield element (1), in particular for lining a combustion chamber (2), having a single-part or multi-part wall (3), which wall (3) has a hot side (4), which can be impinged on by a hot medium, and a cold side (5) situated opposite the hot side (4), and having an encircling edge (6) which adjoins the wall (3) and which extends so as to point away from the hot side (4), which encircling edge (6) comprises at least two opposite first edge sections (56), a second end section (57) running transversely with respect to the first edge sections, and a third edge section (58) arranged opposite the second edge section (57),
   characterized by
   an opening gap (12) which extends through the wall (3) and which divides the wall (3) into a first wall section (51) and a second wall section (52), and by a partition (8) which is arranged adjacent to the opening gap (12), which partition (8) adjoins the second wall section (52) and extends, so as to point away from the hot side, between the two first edge sections (56).
2. Heat shield element (1) according to Claim 1, characterized
   in that the opening gap (12) extends to both sides as far as the first edge sections (56).
3. Heat shield element (1) according to Claim 1 or 2, characterized
   in that the encircling edge (6) and the partition (8) extend as far as a free end (7).
4. Heat shield element (1) according to one of Claims 1 to 3,
   characterized
   in that the partition (8) is inclined at least in the region of the opening gap (12).
5. Heat shield element (1) according to Claim 4, characterized
   in that the partition (8) has multiple bores (13), the axes (14) of which bores (13) are directed towards the first wall section (52).
6. Heat shield element (1) according to one of Claims 1 to 5,
   characterized
   in that, on the second wall section (52), there is arranged at least one fastening device (15) which extends preceding from the cold side.
7. Heat shield element (1) according to one of Claims 1 to 6,
   characterized
   in that the heat shield element (1) is produced from metal.
8. Annular combustion chamber (2) comprising an outer shell (16), a number of heat shield elements (1), which heat shield elements (1) are detachably fastened to the inner side of the outer shell (16), and an annular channel (17) which extends over the circumference of the outer shell (16), to which annular channel (17) an air bypass flow can be supplied and which annular channel (17) has an annular gap (18) which is open to the combustion chamber interior (19), wherein the heat shield elements (1) are arranged adjacent to the annular gap (18),
   characterized by heat shield elements (1) according to one of the preceding claims.
9. Annular combustion chamber according to Claim 8, characterized
   in that the annular gap (18) is arranged between the partition (8) and the third edge section (57).
10. Annular combustion chamber (2) according to Claim 8 or 9, characterized
    in that the outer shell (16) has first openings (20) for the impingement cooling of the heat shield elements (1).
11. Annular combustion chamber (2) according to Claim 10, characterized
    in that second openings (21) for the impingement cooling of the first wall section (52) are arranged in the outer shell (16), and tubes (22) are arranged in said openings (21), which tubes (22) protrude beyond the outer shell (16) so as to point towards the hot side.
12. Annular combustion chamber (2) according to one of Claims 8 to 11,
    characterized in that the heat shield element (1) lies at least in sections, in particular in encircling fashion, with the free end (7) on the outer shell (16); and/or
    in that, at least in sections, in particular in encircling fashion, a sealing means which is elastic and/or installed on the edge (6) is arranged between the free end of the heat shield element and the outer shell (16).
13. Gas turbine installation (23) having an annular combustion chamber (2) according to one of Claims 8 to 12.

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